If we’re specifically talking about mixing, I love the SSL 4000 E. The flexibility it offers is, in my opinion, unparalleled. For the music I tend to work on, I like the “bite” that the EQ and dynamics sections have. Plus the fact that you can drive the individual channels and stereo bus pretty hard.
For tracking, I’m with Mary. The Neve 80 series are my personal fav. I also have at my studio 4 channel strips from and original Trident A Range that are pretty magical on drums.