I tried just about every OD imaginable at one point when I was doing a shootout. I probably drove my bandmates crazy with 10-12 OD pedals scattered on the floor at every practice for a while, haha.
I like the Maxon OD808 better than the TS-9. I used to use a TS-9 but made the switch. I got an OD820 to try against the OD808 and swapped back and forth between the two on songs at band practice a couple times that week. For boosting amps, I preferred the OD808, and it's what I still have on my pedal board now about 3 years later. I like the little extra mids it gives and the way it pushes the amp, especially with low mid heavy amps like Rectos.
I can see where some people may prefer something a little different with upper mid focused amps like Marshalls, but I like the OD808 with it, too. If you want something a little more transparent when clean boosting or that has a little less of a mid hump, the OD820 woudl be more to your liking. If you like the little extra flavor typical TS-type circuits add, you'll probably like the OD808 better.
It's really just depends on what your tone taste is. You can't go wrong with either.