It's really different for every person. I see a lot of MMs and TAFs in the list for overrated, but I would definitely get $8k of enjoyment out of a MM(r). And a HEP restored TAF is the last pin I plan to purchase. Waiting on that for last for obvious reasons.
My only real advice is to go play a LOT of pins from this era and find one you think you'd like to be able to play every day. There aren't really any machines from this era I *dislike*, but there's a number I'm neutral on. Some of my favorites besides TAF/MM are AFM, WH20, Road Show, Fish Tales, STTNG, Congo, Corvette, and Banzai Run. But there's a huge variety of game feels there, you'd have to play them to decide.