I agree with @jester523 on his assessment for all the games. I would just add that Star Wars along with other mode based games could be "difficult" to wrap your head around for beginner players. Steve Richie games "force" you to become a better player as the shots are not forgiving. If you miss some shots, chances for a drain ball is likely.

Iron Maiden is similar as Metallica that it has long ball times and easy for beginners. Given that the playfield provides more shots with the upper playfield using the extra flippers would have it be rated higher than Metallica.

I ended up buying Metallica for my first NIB Pinball machine this month. From your list I have played all but Batman 66. Metallica has been around and has been proven to be a great game. Why? It is because it is very appealing and easy to play for beginners. The shots are forgiving.

It is rather challenging to get to Wizard Mode for the players who want to "beat" the game. Learning how to stack the modes together to get past CIU and deciding to play for End of the Line gives Metallica pinball endless amounts of playtime without it being "stale".

If you play Metallica by executing Sparky, Snake, tomestone, hammer hits... then I can see the game being repeatable and a "drag"...

Either way, any game you get you'll have a blast. You will be able to learn flipper skills to use on any machine and nudging is an art form of its own.

Have fun!!!