OP is definitely in a tough spot. My thoughts:
I walked up to a Rush Pro on location about a month ago. I had no idea what shots to shoot to start multiball. I just shot flashing shots and read the LCD. That being said, I still really didn't purposefully START MB; it kind of "just happened" on its own. When that happens in a game - when I start MB without really even trying - I lose interest pretty quickly. I like a game that I have to REALLY earn that MB. Maybe I just made shots and got lucky - I dunno. Just seemed like every 4 shots or so, another MB!!!!!!
AFM, to me, is that perfect balance of fun:
You have the "bash toy in middle" that makes new players feel accomplished.
The MBs require some work: main one requires the 4 shots in the inner left orbital, Martian MB requires you to nail all 4 bobbing martians, Strobe requires you to progress through SOL to get it selected, and Total Annihilation requires all 4 main shots to be completed at least 3 times each. Some more simple than others.
The wizard mode is not impossible but not a gimmie either. If you're dialed into your shots and know the 6 objectives, it IS doable.
There's enough gimmicks on the PF to keep people interested and entertained.
The Monty Python/Mars Attacks humor and vibe blend very well with some excellent call outs.
These reasons and others I'm sure I missed are why it remains in the top 5 games here while other new "oooo shiney" games come and go. Only IMDN, JP and Godzilla are new games that have threatened it. Oh look, 3 out of 3 of those games are from Keith Elwin. Wonder why? Because his games challenge those wanting to go deeper. His games go outside the box of traditional pinball playing.
JP is a great example: no "skill shot" inlanes up top or traditional inlane multiplers. Critical shots go through TIGHT areas like the left ramp through the pop bumpers on IMDN or the Smart Missle target on JP, and that the Jeep HAS to face left for you to get the Smart Missile, so that shot is ALWAYS going to be an insanely tight shot, but oh, SO rewarding when you hit it. All MBs require SOME effort with T-Rex being the easiest one by a mile to achieve. Outside of T-Rex, you have EARNED that MB. Getting to Dinosaurs Rule the Earth means you have truly conquered the game with Control Room needing to be complete, part of which requires you to hit the Tower...what...15 times? These are some pretty tall orders, and don't even get me started on AIQ. I feel like that is the pinball version of War and Peace when I walk up to it.
Lots of me blowing hot air here, so what am I saying? If you want a fun game everyone can enjoy, get MB, AFM, or MM. There's a reason WHY CGC chose to remake "the big 3" first guaranteed profit as the demand was insane and STILL is - having driven up the cost of originals and even the remakes go for more now. Cactus Canyon seems "up in the air" still. The first 3 were a slam dunk, guaranteed revenue churner. CC, jury is still out for me on that one.
I'd honestly say a Keith Elwin game isn't going to have the staying "family fun" power. His games are absolutely geared towards the intermediate to advanced players. You'll be playing "coach" to help the rest of the family get into it, which can be fun in and of itself. Just be ready to be playing alone or with other more experienced pinball players if you go with a KME game.