I have been to about 50 of the 92, and by far my favourite so far has been Hillsborough (and thats saying something as both times I have been there we have conceded in the last minute to lose points).
Loftus Road. Great compact ground that can generate a good atmosphere even when only half full. Not perfect, but a football stadium with character and history.
Millenium Stadium Cardiff was by far the best ground I've been to.
Goldstone my best memories / most enjoyed
I actually like the Mad Stad
Also high on the list are Forest and West Ham.
Don't seem to have been to many in the Premiership that haven't changed dramatically since I last went there (e.g. Stamford Bridge - last visit was the Ron Challis game!)