Is it a tube head?
When tubes distort, there's natural compression.
I like the soft compression available in the Fulltone Full-Drive 2 OD pedal; but, I'm unaware of a stand-alone compressor that I like.
These things are simple to use, feature a Hi-Z input on the front, (thats high impedance, ie., guitar), relatively inexpensive, great quality, and plug into the wall direct. (No wallwart.)
I love mine. Its the first stage in my signal chain. (Makes a great "buffer". Has more than enough drive to handle any effects chain.)