I have both so I couldn't tell you which one. Both are really great games and have excellent rule sets. Some of the best rules in pinball, albiet different. The theme integration in LOTR is one of the best in pinball. The shot flow and ruleset in DI is one of the best in pinball. Both get played regularly, and likely both will not leave.

IF I had to pick only one. I would probably go with DI as the ruleset is probably a bit easier to digest and the games don't go for so long.

Sometimes it's fun to play a long game and try to get everything that LOTR has to offer. It's the game that I play when I want to hit smooth shots without having to try too hard (and "coincidentally" enough, feel better about my mediocre pinball skills). It feels very good.

If you like more challenging games with faster ball times, then LOTR is not for you. But nothing beats TTT MB and you're nailing jackpot after jackpot and Gimli is screaming Double Jackpot five! Double Jackpot six! etc. Or that one time you finish FOTR MB and Gandalf yells "You shall not pass!" Nothing beats it.