For what purpose ?
I have AH and AD. Sound different, AD is noisier, but with much more gain, more appropriate for guitare level, but I liked AH with guitar too.
For dirty hardcore drums I prefered AD.
AD after AH was better that the opposite for me, for post filter distortion.
I may buy a 2nd AD for stereo.
After AD, I sold Mxr Fullbore Metal, Fulltone Ultimate Octave, Boss Ds1 Japan.
I keep my Nitrogen21 french germanium fuzz and T-Rex Gull Wah.
For AH you have to consider filter, really precise envelope follower/trigger with many destinations, lfo, exp pedal inputs, full midi control (except trigger! ) dry/wet…
It can be a good wah, autowah, tremolo, slight phaser, self oscillator for kicks, other synths sounds…