AFM and MM have a similar layout but play differently, as you mentioned.
AFM is faster and more brutal. Strobe multiball is unique. I love the risk reward of shooting the mothership. That ball can come back fast! Perfect rule set that is easy to understand but very difficult to complete. Can be approached in different ways for scoring as well. Love the campy humor of this game and the jiggling martians. And the large faceted inserts glow like jewels, especially with LED lighting. I like the color red in pinball machines and this game has a lot, and it really pops with the complementary green next to it. Beautiful to look at. You can tell the team that created this iconic game was confident and working at the peak of their powers.
MM builds on its predecessor and refines it in some ways. The trolls are a blast and add a lot to the game. Love getting troll madness completed and hitting the trolls as they alternate popping up. Catapult ramp is very cool, as is the castle. More variety of callouts in this game with all the different characters.
MB is great with lots of toys. But overall it seems simpler than the other 2. Rules are not as varied or interesting. Much easier to complete, which might be better for average players like me. I would actually have a chance of finishing this game. Not sure how I feel about that.
I haven’t gotten tired of having AFM and MM as my 2-game collection. I had 3 modern games before which I did get tired of and sold or traded to get these. If I was going to buy a 3rd game it would definitely be MB, but I’m OK with just having the first 2. I think they are a little stronger overall with their gameplay, rules, callouts, and humor.