For fishing i like sit on top styles because they are easy to fish from. But for rapids there is a completely different style of kayak. Fishing kayaks aren't really made to handle much more that class 2 rapids. Sit in anglers are harder to fish out of and if you tip are harder to get back in. And during the heat of the summer when it gets to the 90's i like to jump into the water.

I use a Cobra Fish'n'Dive kayak, a sit-on-top, and it serves me well. I don and remove much of my scuba gear in the water but, having removed my BC and air in the water, it's sufficiently stable to climb back aboard and drag my gear aboard after me. I also use it for fishing, and there are places to stow and attach my tackle and gear. Sounds great, eh?
My wife uses a Wilderness Systems "Shaman" - there's a photo of her paddling it in my profile - and it's cuts through the water faster and easier than my kayak, but it's not as stable.
You have many choices for good kayaks, and a lot of interesting research ahead of you, but sort out you preference and performance priorities and please do NOT purchase a kayak without paddling it first!