I really like my HBE (check it out. I got my Psilocybe for $140 new), and I'd like another Small Stone, but the ones I gravitate to most often are my Phase 100 and especially my EVH Phase 90. Some folks don't like the EVH and I agree that the '74 Reissue sounds a "bit" nicer (but doesn't take an adapter), but I really-really love the script logo/block logo button on it; I spend equal time in each mode. It's a ubiquitous unit that you should try in addition to the Phase 100, Slow Groove. Don't give up on Phase 90s, even if you're not doing Van Halen. The EVH model will give you a good idea about them due to the "script/block" switch. A one-knobber that's been around 35 years should not be disregarded. It's comfy and brings grins. "The Rover", anyone?
The 2-stage Phase 45 will be hard to find but there are clones like the MojoHand Nebula. The Diamond and Whetstone models (check these out) have 2-stage modes I believe, and I think they even have asymmetrical settings for getting vibey.
The Red Witch is subtle. Nothing dramatic. But it has such a pleasing warmth, really soft. And it's big bucks. The PH-350 is designed for stereo, and--at least based on clips and forums--doesn't seem to be as "strong" of a mix in mono, but I haven't brought one home. As I understand it, it shines in stereo, but though it has a thick sound, especially in 10-stage mode (naturally), the thick sound has that "riding on top" characteristic in mono that stereo phasers all seem to exhibit in mono. But again, I haven't actually tested a PH-350.
As for the envelope-driven phasers (Pigtronix, Stereo Polyphase, Phantasm, Akai) the only ones I haven't sratched off my list are the Akai (can't find, out of production) and the Pigtronix EP-2, which isn't available yet. The EP-1 gets like-it-ok/hate-it reviews, but more importantly I haven't been able to find one to try even from Pig dealers. The EP-2 is promised as an improved version so I decided to wait.
As has been mentioned, a good Small Stone *and* Phase 90 will cover most of the kingdom. The HBE is a minor miracle though, and BOSS-priced. It's a tweaker, but it can imitate a 90 and much of the Stone's territory, as well as get asymmetrical and do undulant, detuned, wobbly vibe stuff. At faster speeds it's just like a tremolo! Playing in time with the rate will make you cry. It's not as tubular as a Phase 100 though. I haven't found anything besides a 100 that can do what the 100 does for that hollow hoo-hoo "Shattered" sound.
Slow Groove, is this for your sludge-rock doom stuff, or for some cleaner business? A word of caution, phasers are addictive. I want most of them, and there are so many! If I had to pick 2 only, it'd be a 100 and an HBE. I think those cover the most ground, both FET-based sounds and OTA/optical-based sounds -- most everything except heavy 12-stage phasing (Moog, PT-9 Pro). If I could only have 1 to cover the most ground, it would be an HBE Psilocybe. Yet my favorite is the EVH Phase 90. Opinions subject to change without notice.
I don't know if you've narrowed down whether you prefer FET or OTA, or how many stages, or how fast or cosmically slow you want to go, etc. but you did say you wanted a phaser that can do asymmetrical vibes. For that the overwhelming bang-for-buck answer is the HBE. But if you can, check out the Diamond and the Whetstone also, each of which has multi-stage features.
