I've owned several phasers like Phase 90, Small Stone, multi-effects pedals and boutique stuff like Grand Orbiter and HBE Psilocybe. They're all pretty good on bass, but Phase 100 is the one I always come back to. It's the most unique one (not a single boutique phaser is based on it), and it simply sounds the best on bass guitar to me.
It has a rich, detailed voice that never turns into mud for live application (unlike many dark sounding OTA and Opto phasers), and it absolutely NAILS the "For the Love of Money" tone unlike most other phasers I had. Part of that tonal uniqueness is the fact that it's a 10 stage phaser (6 modulating + 4 fixed). It's very liquidy, and has a bit of flanger-like quality to it as well. In comparison to say Phase 90, it doesn't have the same low mid bump and so I find it more pleasing in the mix and less grating. It works really well with dirt and fuzz pedals, as expected.
I haven't noticed any tonal loss when it's off, even though it's a hardwire bypass and not a true bypass, but I tend to have a good buffer in front of my board and at the very end. You can't really go wrong with MXR phasers in general. Let me just leave with this quote: "Favorite phaser? The orange one."