I don't have space for a deep collection, but I think Whirlwind is a great choice and compliments a Richie table for something different. For me, System 11 is the sweet spot of pinball, faster gameplay than an EM, and it doesn't feel like a video game of the DMD era and beyond. I like games than anyone can pick up and play for when guests are over. For a deeper game, Road Show would be my next choice, but with the talking heads, the machine feels like it would be a PITA to service for a novice like me if something were to go wrong.
Edit: You can forget about any suggestions about Funhouse, you'll be lucky to find one under $7,500 because of the 2.0 code update. I think you would want to keep the High Speed if you enjoy playing it.