Agree with demo, but I don't think you really know what you want out of a kayak without six months or so on the water experience.
For your first kayak; I'd get a cheap, relatively light kayak that is safe for your weight + gear capacity. Experiment with it, do a bunch of DIY mods, take it to multiple different lakes with different fishing conditions.
You will make mistakes with your first kayak; might even not like kayak fishing after a few months; you will find out where and how you like to fish from a kayak. Might as well make these mistakes with a cheap kayak.
Then, after six months or a year; consider buying a more expensive kayak based on your experience. You might end up keeping your lighter, cheap kayak for rivers/shallow water/difficult access/ heavy vegetation waters and using your more expensive kayak for bigger waters.
I agree with this. Definitely make an educated decision about what kind of fishing you'll be doing and what kind of kayak will work best for that. Go cheap, and more specifically, go used. You'll get way more yak for your money if you buy used. Then after you spend a good amount of time on the water, you'll actually know what you want.
A lot of people don't know how they'll actually end up using the kayak. It's hard to imagine if you've spent your whole life stuck on the bank. Someone might be blown away with the stability of a particular yak at a demo, but end up really disappointed with the lack of speed if they end up chasing whites and hybrids on open water.
oh yeah and do some testing as well.