I'm a Keeley compressor user.
Ultimately, I find the difference is mostly in the preference on whether/how much the high frequencies are filtered off.
The Keeley filters the high end to some degree and for my purposes, it works great when I use it to add sparkle yet tame the hign-end when playing chordal stuff on Fender amps.
To others, especially country players, this filtering is unacceptable.
As in all subjective matters, YMMV.