I think it depends on the size of the collection really and personal preference of course. I have TZ, MM, AFM, WH20, Congo, IJ, TAF, TS, and CFTBL. I really like all of them and don't want to sell any of them. I love different aspects of the layouts, artwork, gameplay, callouts, music, game features, etc... There's a lot to love in the 90's games.
I'm usually playing 3-4 pins at a time, so I rotate around and I don't really burn out on anything. They aren't as deep as modern games, but I like that variety and like the simple ruleset games. They help balance out newer games. I don't want every game I own to be super deep.