Slow your roll! Everyone on here is going to tell you to demo some first, which is definitely the right answer. Call Mariner Sails and see when they have demos going on. I know they have one scheduled on April 25th at Little Elm Park on Lake Lewisville. Go there if you can and try out a few different ones, you don't want to buy a kayak that you'll later hate.
Your age, height, and weight factor in. What type of water you'll be fishing factors in. Your budget for kayak/PFD/paddle/accessories factor in. How you will transport it may affect things. Talk to the experts, demo, buy, and have fun.