The first compressor I bought and still have, is a Fairfield Accountant which is definitely not transparent. On my board, with a bit of experimentation, I discovered it's a unique effect with a wide range of tone shaping possibilitities beyond basic compression.
I use it as both a limiter to rein in distortion pedals, and for its subtle/sometimes not so subtle tone enhancing capabilities. It's hard to describe, but when needed it thickens up my sound in a pleasantly dirty way - and its basic controls make it quick to find a satisfying tone.
When I don't want noise I use my other compressor, but the Accountant remains a filthy favourite!
Pricey, yes, but IMHO this mini pedal was worth it for the range of sonic possibilities.