TSPP, LOTR and SM are Sterns top 3. TSPP, lots of stop and go but the best rules of any pinball ever. I think LOTR is in the middle, decent flow, good rules. SM has the best flow and the most fun shots of any pinball I've ever played. However there isn't much to the rules.
I've owned TSPP, I've got a ton of time in on LOTR and I currently own SM. I believe all three of those games are about as good as the next, it just depends on what type of player you are. I'm a speed freak so I love SM. I'd like to own another TSPP both for the crazy good rules and I like the theme. LOTR is very good as well but I'm not into the theme and feel if I own TSPP and SM I can live without LOTR.
That's just me though.