Dannyboy, it sounds like you need to figure out what you're going to do with the pool. I've had a 15' round Intex and now have a 40' long pool you can do laps in (and I do). So I've been at both ends of the spectrum.

So...who is going to use the pool, and how? If all you want to do is relax in floating lounge chair listening to a ball game or your favorite music, I can tell you it fell just as good in my Intex as it does in my FantaSea.
Are you going to entertain grandkids? Then maybe a bigger pool is in order (though Intex Donuts go up to 18' rounds...and other brands go bigger!) Other adults, including seniors? Then something with a deck would be good.
Water therapy? Exercise? Laps? Just cooling off?

All this goes into the decision mix.