It must be Spring because another blog on kayak materials just blossomed.  If you are thinking about getting a new used boat here are some things to think about.   
    First up, plastic.  You may call it polymer or rotomolding, but it's plastic.  For 90%+ this is the material of choice and if you don't have a requirement that pushes you toward a different material you have already found your home.  Plastic is the cheapest material covered in this article, yet still one of the most durable.
    Plastic isn't perfect by a long shot.  Plastic boats can be flexy in rough water.  They tend to be heavier than their hard-shell cousins and have been known to deform under weight and/or heat.  The finish isn't as nice as other materials  since regular plastic just doesn't shine.
    Fiberglass suffers no such issues.  Fiberglass looks great, weighs less than plastic, and resists flexing and deforming.  With 'glass the paddling is generally more direct and feels very solid but think twice about that beach landing or navigating a rock garden.   Fiberglass can crack and scratch in a way that plastic just doesn't, and a glass boat may cost double or more what a comparable plastic boat costs.
    That leaves the exotics and hybrids.  Let's consider Kevlar.  Kevlar is exactly like fiberglass except that Kevlar's properties allow for a thinner hull that is just as strong as 'glass.  That means Kevlar boats are lighter, but weight is a funny bowling partner.  A fiberglass Current Designs will be as light or lighter than a Kevlar Wilderness.  Current builds a boat just above the minimum strength standard (thinner materials) while Wilderness builds a boat just under maximum strength standards (thicker material).  The only real rule is that a comparable boat from the same manufaturer is 5-10 LBS lighter in Kevlar than fiberglass for a $500 - $1000 premium when new.  That's $100 per pound when most of us could just skip a meal or two for the same weight saving results.  Short of lifting a kayak onto a roof rack, what difference does a few pounds make?  If racing is your passion you can always find a race-specific boat generally built a bit fragile, light, and without frills.  For touring, recreation and fitness wight isn't going to change all that much in performance.   
    There are some variations on plastic worth noting.  Companies like P&H and Prijon use techniques to build plastic boats that are sturdier and stiffer than the competition.  Both companies products are worth a look but the technology comes at a small premium.  Even the standard roto plastic boats have gotten quite good anymore, and are less prone to the deformation issues of boats from fifteen years ago.
    You may also consider the new high-density polymers that look and act a lot like fiberglass but are in fact a thin walled, high quality plastic.  Boats like Eddyline look great, are extremely light, resist scratching and have crazy durability.  While these boats aren't quite as stiff and unflexing as fiberglass they are better than standard plastic.  Note that the pricing is closer to fiberglass in most cases.
    The bottom line is that plastic is the first line of defense and the natural choice if you aren't sure.  High quality, high density plastics are great if you can get a boat in your budget.  Fiberglass makes for a great paddling experience but only if you are prepared to be more careful.  Kevlar is nice, but fiberglass is very nearly as good.  


    
   

    When it comes to equipment - specifically boatsNbikes - I tend to have a short attention span.  What I mean is that I am always looking over the horizon for the next one to try or buy.  It's not as if I can't commit, after all i have been happily married for 15 years and together with my wife more than 20, it's more that I really enjoy dating kayaks and bikes. 
    That's why I don't buy new, or almost never.  With new stuff I buy it, I try it, I get bored, I sell it, I lose money.  Call me crazy, but I hate to lose money.  With used stuff I buy it, I try it, I sell it and I break even or lose/gain a little.  SOOO much better. 
    The other reason I love used is that I don't have to cry over the first ding or scratch.  It's a sickening feeling to put a blemish on a perfect bike or kayak, but if they guy before you did it already a new boo boo is no biggie. 
    With bikes, at least, I have settled down a bit.  After owning and riding 36 different bikes and swapping steeds at least every season for ten years I know exactly what I want and what fits my size and style.  The thing is it really took until mid-life with lot's of trial and error to figure it out.  If I had done that at full retail I would be selling pencils in a can by the Art Museum - AND I wouldn't have been married for 15 years.
    It can be a challenge to find what you want on the used market but if you are vigilant and patient almost everything comes up for sale sooner or later.  The musical stylings of Ebay and Craigslist have changed the world. 
    If you have already dated around and you know which kayak or bike you want to settle down with then you might buy new.  Otherwise save your money and save the natural resources by picking up pre-loved and recycled model.

       So which is the best choice in a kayak?  You can choose between rudder, skeg or sleek minimalism.  There plastic, polymer 'glass and kevlar. Even long and short hulls and hard or soft chine. The debate goes on with fish and swede forms, but what about simple fun as a factor?
        Performance can be a slippery mistress when the powerplant is the human body.  I have been passed by folks in heavier, wider, boats and cheaper, clunkier, bikes.  Often, in fact.  I paid more but they are going faster and perhaps having just as much fun.
       Take my own experiment as an example.  On a Monday I paddled my local 5.2M loop in a narrow-long performance oriented Eddyline Falcon s-18.  Smooth, no wind, warm.  It was a 1 hour paddle, typical for that loop in faster sea kayaks.
       On Wednesday I take the same loop in similar conditions at a similar time of day at a similar effort.  This time I use a 14' plastic Prijon Calabria.  Nice boat, but shorter and wider and heavier and more stable.  The difference?  About 3 minutes.  I recognize this is not a perfect experiment, but it does show that equipment-based performance is nominal for the recreational paddler once you reach a minimum standard of equipment performance.  That is to say that the performance difference between good equipment and great equipment isn't as big as the talk-time we give it.
        Now don't get me wrong, 4 minutes an hour is HUGE if you are racing or trying out for the olympics.  Even if you are touring that could add up, but for the common man the Prijon would be as much or more fun than the Eddyline.  It costs less, is more stable and really comfy. 
       To be honest, the Eddyline WAS more fun for me.  I just like the feel of a narrower, longer boat, but my point is that it's more about FUN and what you like than arguments about miniscule performance differences because the differences are generally miniscule.
     If you are looking to buy a kayak he definitive best choice for a kayak is the one that gets you outside and that you have FUN in.  Don't overthink it.  Nothing is perfect and making a good choice will rarely be much different than making a great choice.  Just have fun.

The other day I watched a YouTube video that provided a great animation of a 29" wheel going over obstacles better than a 26" wheel.  There it was in black and white, definitive proof that a 29'er will outperform a 26'er when going over animated bumps - and real bumps for that matter.  The problem is that there is more - much, much more - to the 29 vs 26 equation than bumpability.  If it were just about big wheels going over stuff we would all ride Motobecanes built onto Monster Truck wheels, which I have to admit sounds kinda cool now that I wrote it.  Anyhow, let's disect the 29 vs 26 argument AGAIN.
I am the proud owner of a 26" front suspended cromo Kona Hardtail Team Bike from the mid 90's as well as a modern 29" front suspended cromo Hardtail GT Peace (geared, not SS).  On paper these two bikes have an awful lot in common.  They are both multi-geared ridgid-butt steel mountain bikes with suspiciously comparable angles.  This makes them perfect to compare 29 vs 26 in the rubber-meets-the-dirt world.
Let's start with bumpability.  The GT just goes over stuff like a hijacked tank.  Head on obstacles require less body english than the Kona, but we knew that already thanks to the magic of YouTube animation.  The 29'er is also easier to keep at speed due to the increased wheel circumference.  It likes to keep motoring along.   The 26 just doesn't roll as fast or as easy, but while the increased wheel circumference likes to keep going it also tends to keep the GT going straight.  The smaller Kona wheels with their smaller diameter steer quicker and feel more nimble. 
In fact, the Kona feels more nimble all around because not only does the increased circumference of the 29" wheels slow handling, it also puts added weight in the worst possible place.  29" wheels have more rotational weight at the outermost edge of the rotation than a 26" wheel does.  Added rotational weight means that every time you spool up or slow down those big wheels need to overcome added inertia.  I am no weight-weenie, but don't poo-poo this one.  When you accelerate or decelarate everything on the bike speeds or slows together, but wheels ALSO must spin.  Saving weight at the wheels matters more than weight on the frame, and the Kona feels like it accelerates quicker. 
Finally, the added wheel size of the GT requires more frame material and a longer wheelbase, putting on weight and adding to the slower feel of the GT.  Slower handling isn't all bad, though.  The advantage is that the GT feels more relaxed, less squirelly and generally more stable and sure-footed than the Kona.
There are two things that I didn't notice.  First, 29" wheels require more energy to stop, but that didn't show up in the actual performance.  Second, a 26" wheel is stronger than a 29" wheel but I have not had reliability issues with either so we'll chalk both braking and strength to non-issues for this test.
So here is the bottom line.  For tarmac and hardpack roads, rails-to-trails, West Coast fire roads, jaunts to the coffee shop or an all-day tour it would have to be the stable and faster GT 29. 
For technical mountain biking, East Coast switchies, competitive rides or a faster workout it would be the Kona 26. 
So which is right for you? The one that gets you out riding.