TZ - My favorite, all time.
ACDC - A simple layout with excellent rules, and endless scoring strategies.
WOF - Nudging. Nudging. Nudging. Really interesting and unique rules even though I dislike the theme.
IM - Open, fast, and leaves you frustrated and wanting one more game.
TSPP - Up until recently, I disliked this game. But if I only get 10, I know this is one of the deepest and I can't think of another game with a wider variety of shots.
WPT - Huge open playfield. Drop targets galore. Unique and interesting rules.
AFM - Great humor. Simple gameplay. Accessible to all. I actually like MM better, but the inconsistent kickouts from the moat and STDM castle drains annoy me and I want to use this slot on something nice, easy, and predictable.
SM - This might be the game I have the most fun on consistently. It feels like I can keep the ball alive forever, but in a "this is rewarding" way, not a "this is easy" way. Great theme integration.
CFTBL - Love the look, sounds, theme integration, unique layout, and superb, but simple rules. Most games feel "over" once I've hit the big jackpot. With CFTBL, I just want to work back through to it again.
T2 - Nostalgia. Before last year, 90% of my lifetime plays were on T2.