I've been playing quite a few games lately. This has prompted me to reevaluate some of my ratings. The following games--which used to be 9's---are now 10's for me:
Liberté: On the surface, it may seem like a simple area majority game (El Grande) using cards to determine where you can play (China). There's so much going on in this game, I would need multiple posts in order to do it justice. You can plonk down a big pile of influence in order to make it last or spread it out to gain more success with that faction in the short term. You can go all out for one faction, or do a little in each. You can try to manufacture a Radical Landslide or a Counter-Revolution. The card management is complex, and the action decisions (play a card or draw a card) are agonizing.
ASL Starter Kit #1: Advanced Squad Leader has made inroads in my gaming circles. While I have yet to discover the joy/torture of Guns and Tanks, I have been able to teach and play more Starter Kit scenarios. The ASL system is simply the best WWII tactical game system I've seen. Everything else I've played--from Memoir '44, to Tide of Iron, to Conflict of Heroes, to Combat Commander--seems like a cheap knockoff. There are many excellent sources of information out there, including Russ Gifford's ASL training sessions and Joe Steadman's recent video series.
Tichu: I play Tichu all the time, and I always want to play it. There's no better 4-player team game. It is a card game, so there's always the element of chance that can throw a hand one way or the other. It is unlike my other top games in this respect. But it's so fun to try to make a desperate Tichu, or to set a solid one.
Napoleon's Triumph: I had played Bonapart at Marengo a few times before buying Napoleon's Triumph. I liked the system, but I wasn't too fond of the small map and limited options. NT blows that out of the water with its huge board, more than double the number of units, and more ambiguous goals that are somewhat under control of the French player. The mechanics are certainly very abstract for a Napoleonic grand tactical game, but the position-and-maneuver-focused choices are awesome. The uncertainty of the unit strengths and types, as well as the threat of breaking through the lines and/or flanking, keeps the tension very high and your plans very flexible.