I told the big compressor thread, but never told youse guys.
Broughton Omnicomp was my winner over the following pretty durn good selection. I chose these as representatives of different technologies for the compression:
Empress
Becos Stella
Tranzformer
Lusithand Alma MkII
Doc Lloyd DLA-2A
I'll tell you why I prefer Omnicomp over second place Empress.
In compressor threads, I think sometimes "transparent" means "very subtle transition between uncompressed and compressed", but a stricter definition is "sounds like my bass straight through, and also very subtle transition to compressed". I think Omnicomp better satisfies the latter, while to me Empress adds a little sweetness that I don't necessarily want.
Quiet operation was an essential priority.
(As a compressor, I also chose Omnicomp ("for cleaner lows") over Effectrode LA-1A , but the latter is a keeper for other reasons.)