The majority of people, specifically novices, are typically much better off with a rigid kayak. Inflatables do have their usages, but firm hulls are just a lot more flexible - specifically if you prepare on heading out on the open sea. An inflatable kayak would certainly not be my front runner if an interested shark decided to take a test bite from my kayak!
With that in thoughts, consider where you will be fishing. If you intend on going to the sea, which requires primarily straight-line traversing distances with few turns, a lengthy and also slim kayak is better. If you intend on angling in a smaller lake or creek, a shorter, larger kayak is the means to go.