Combination and variety are the spice of life!
Going back to
AFM - a really nice original ( non fade screen printed cab ) or a mint restored
AFM are 6k plus all day long. Condition is always biggest issue with price variations.
As for games - I sometimes get as much buzz playing a 50's or 70's Gottlieb as a modern Stern. Noticed my 16 year old will never play my modern games but he loves a 1978 EM.
Also the classic Sterns around 1980/81 when set up correctly with rebuilt flippers etc are fantastic. Finding them is near on impossible - been searching for years for a few titles ( in great condition which makes it super hard ).
Not had a chance to explore other 80's games, Gottliebs and classic Bally's. Do like Centaur a lot.
The bigger the collection, the more variety I look for.
But, if I could only have 1 game, it would be a modern Stern as code depth would ensure longevity.
I have over 1000 games on KISS - not got close to Rock City and not bored of the game at all.