I’ve been using Cinestill D96 Monobath for black and white film developing recently. I still think Caffenol is the better option in terms of environmental safety, but the convenience and speed of a monobath can’t be beat: 8 minutes to develop and fix film, followed by 3 quick rinses and a short soak in distilled water/rinse-aid and you are done.
It’s temperature-sensitive, so you need to warm it up first, but even so you can realistically develop, fix, and archivally wash BW film in less than a half hour.
And as far as I can tell there is no downside, aside from the cost (~$20 per liter, which can develop 16 rolls of 35mm or 120 film, or 64 sheets of 4x5 film), and the need to dispose of it safely somewhere once it is exhausted. I think the negs look just peachy.
I mainly shoot HP5—rated at asa 200—these days, so the method I use is this one (after pre-wetting for 5 minutes in water at the same temperature as the monobath):
normal development: 75˚F for 8 minutes*, with minimal agitation†
pushed/higher-contrast (for alt pro contact printing): 83˚F for 8 minutes
*As per the monobath instructions, you are supposed to add 15 seconds per previous roll developed to the 6 minute minimum processing time to account for the gradual degradation of the fixer, but only up to 8 minutes total. I just simplify things by developing all rolls for 8 minutes.
†My approach is slightly different than Cinestill’s: Agitate gently and constantly for the first 30 seconds, followed by 5 inversions at the top of every minute.