A final dungeon should have the strongest random encounters in the game, good bosses, and lots of equipment you need to go out of your way to get. I think FFXII was the worst, then FFX. FF3, 4, 7, 9, and X-2 were all pretty good. X-2 wasnt as good as the others, but the puzzle at the end is really fun and the aeons you fight are good bosses.