In general today most plastics are pretty solid. Your main choice will be to go crosslink or linear. In general crosslink(riot, jackson) and scratch less but cracks easier. Linear (fluid and most other) will be slightly less stiff and scratch resistant but will have less chance of cracking from hard knocks.
Crosslink kayaks I have broken 2, linear kayaks I have broken 0.
I have not seen or paddled LL or BlissStick kayaks. But between the current models of Riot, Jackson WaveSport and Fluid play boats I would go for Fluid.
Fluid nemesis. here is a review:
adrian.playak.com/index.php?option=com_c...=view&id=80&Itemid=5
here are a whole bunch of clips of the Nemesis in action
whitewashed.ning.com/profiles/blogs/gats...freestyle-photos-and
I have had my medium nemesis for 2 seasons and it is holding up well. Paddle mostly on rather shallow rivers and play lots on rocks. After 2 seasons it only has the standard scrapes and scratches, no serious loss of plastic. I have also been stopped abruptly by various rocks and still no sign of stress cracks developing. In my opinion my nemesis is holding up better than my previous wavesport and riot kayaks.
even after all of the above try and demo some kayaks, the one that you like the feel of the most is the one you should get.