1. LOTR - Combination of theme, rule-set, and immersive sound/voice package. This is what a "complete" game feels like! I had one for many years and sold it just because the game times got too long and with a new baby I had no time for long games. I also feel with most of Keefer's games that I eventually "hit a wall" in that I get really far in every game and then get stuck. In LOTR that wall was completing both Fellowship and ROTK MB in the same game.
2. SM - Best layout on a modern machine, Awesome rules that are designed for both novice/expert players. SuperHero Wizard mode is one of the best in pinball. If I liked the theme better it would be #1
3. ACDC - 2 words "Song Jackpot". The risk/reward of being able to score huge points on each ball is awesome. Take away the song jackpot though and I don't think it even makes my top 10 Stern list.
I'd give an honorable mention to TSPP which has almost too much depth/stacking for its own good.
After these 4 games there's a pretty significant drop to my number 5.
If you're still reading..
5. Metallica - I love the CIU modes, Blackened mode, and strategy of stacking Fuel to build up big scores. What I don't like is all the front-end chopping wood and the layout to me feels clunky in comparison to a Steve Ritchie game. Play Met and then play SM or ACDC after and you'll know what I mean.
6. Tron - I have a blast playing it but it is too shallow to consider owning. It's also not as butter smooth as SM or ST. I appreciate the difficulty of the "Gem" shot but I don't like the way it often exits SDTM.
7. RBION - Great rules, unique layout, quirky Lawlor fun. Theme/sounds doesn't do much for me but to me this is Stern's version of TZ.