Phaser is an effect I use very rarely (same with tremolo, but I love the effect, mostly at slower settings and mostly with clean tones). I tend to be more in the chorus (and sometimes) flange camp (although I don't tend to use flanging for those exaggerated jet airplane effects, but more ad an envelope filter (?), and with cleaner tones.
The only dedicated phasers I've ever owned were an old BOSS PH-1 R, back in the 80s, and now, a Source Audio Lunar. The Lunar is very flexible. I know it's a digital box (for all you analog purists, out there), but it seems to fit the bill just fine, for my needs.
Their Mercury flanger is cool too, but I really love my old MIJ BF-2 That just has a
sound that I've always been in love with.
I've had the Lunar for about five years or so.
No complaints!
With very few exceptions, I tend to prefer modulation units that are stereo-capable. The same holds true with my reverb and delay units. Once in a great while, I'll buy a mono unit, but with the intention of pairing it up with a stereo unit, further down the chain.