My 'top 10' varies with my mood and who I'm playing with, but these are probably my most common 'top 10' overall.
1 Battlestar Galactica
I'm a fan of the (new) TV series, and this game really gives the flavour of the show. I like that it is a team game, but you're not sure who is on which team - plenty of opportunity to role play, and this game is a pleasure with the right group.
This is a relatively new game, but a firm favourite, scaling well with 2,3 or 4 players. A fast-playing fantasy 'empire' game with asymmetric races - but the rules are not overly complicated.
3 Race for the Galaxy
My favourite 'filler' card game, portable and replayable, works well with 2-4.
4 Combat Commander: Europe
I usually don't like tactical war games - but this is an exception. A fantastic system that introduces all the chaos you'd expect squad level action to be, think Band of Brothers as a boardgame. The random scenario generator is excellent.
5 Navia Dratp
My favourite abstract - a shogi chess variant. Cool figures with special powers, resource management (collect power as you move/take pieces, use the power to improve yours) and multiple routes to victory - kill your opponents' navia, get your navia to the opponents end line or collect enough resources. You can play with the starter pieces or build your own 'army'. Definitely a brain burner, this is the only game I refuse to play if I'm feeling mentally tired.
Great 2 player card game. It feels like a collectable card game with lots of clever interaction, without the need to build a deck or collect random packs of cards.
Great business game system. I tend to prefer the titles which highlight the stock market (such as 1830) or that have a relatively fast end game over those titles where the stock market is very static and/or the final operating rounds take ages with lots of recalculating of routes.
8 Age of Empires III: The Age of Discovery
My favourite 'worker placement' game - multiple routes to victory, lots of interaction and variety in the game. The 6 player version (with the expansion) is nicely brutal.
9 Fairy Tale
My favourite 'draft' filler game, you get a hand of cards, pick one and pass the rest on. You can play just optimising your own collection, but once you get more experienced, you'll start to notice the cards being passed and then the game moves to another level. Much prefer it with the advanced 'storytelling' cards - makes the game more interesting both mechanically and thematically.
10 Fury of Dracula
I own both the Games Workshop version and the FFG reprint - similar but different. In both cases it is a team game, hunters vs Dracula and plays great as a 2 player, or with the full complement (but I'm not so keen with numbers in between).
Both have the feel of the novel, with the Games Workshop version being a hunt (you really have to search for Dracula) and the FFG being more of a chase - it's easier to work out where Dracula has been, but harder to pin him down. Combat in the GW version is very much left to chance - if you track down Dracula and it is nighttime, good luck... the FFG has more control.
On balance, I think the FFG version is a little better, but I enjoy both.