I've paddled hundreds of different kayaks, but if you just want to lounge around a lake, or float down a lazy river you wont see any significant performance jump that impacts your enjoyment with a more expensive boat. Durability may be another question, but for your uses that shouldnt be a problem either.

If you got a better boat, however, your gain skills that lead to more enjoyment and more obsession. That's how I got started, I had access to a performance boat that we took over to the lake, just to have fun, but slowly learned skills, then got my own boat, which took me many places and met many many good people.