I've always considered myself a Williams fan but mostly focused on the 60s games. There are a bunch of 70s games I've never played. I'd love to put some time on a Rancho, Argosy, Hot Tip, Wild Card or Big Deal.
I had Space Mission and Grand Prix. Both seem to get a fair amount of respect. With that said I wasn't a huge fan of the slot kickers on Space Mission. I think it would be so much better without them. Grand Prix is fast and fun but so spinner heavy it can get a little repetitive after some time.
Right now I seem to like 50s Gottliebs, 60s Williams and 70s Ballys the best.