The G.O.A.T. isn't really up for debate (darn plumbers, ), but maybe
a G.O.L.D. (Greatest Of Last Decade) award would be interesting. Say, extend it to include year 2k on.
*choose the grouping in the poll, then drop the specific game as a post*
I think I'd go with Resident Evil 4 or 5. They aren't really superb as survival horror, but I thought both were really fun (especially mercenaries in RE5!).
Another possibility is the Smash Bros series.
And I'd rate the Metroid Prime series pretty high, if only for the sweet environments. Not Metroid Other M.
Half-Life 2 must be somewhere in the running. (And it's a traditional on-the-rails FPS, not action/adventure. Action/adventures tend to have rpg elements.)