Dale is the main other human kingdom (unlike, in, ugh, the Hobbit movies, it became a full out kingdom with Bard as king). There's also the Woses.
So, some of this is half estimating from stuff, as Tolkien kind of dances around firm numbers, a whole lot.
Individually Rohan probably had 20,000 troops around the time period this thread puts forward. Gondor probably thus something like that? Estimates for the forces of Dale as built up kingdom are all the crap over the place. I think one place gives them at 20,000 but that feels wacky to me. I'd be more comfortable with 5k. If someone comes by with "Tolkien totally said 20k", that's that though I guess.
If you figured various elf and dwarf kingdoms had 5k worth of troops each that wouldn't feel off to me. Though apparently there are places that give them well higher numbers so I guess that's my personal view. The Dwarves mostly had Erebor as a kingdom by LoTR times if I don't recall wrongly, though apparently there were dwarves in the iron hills and blue mountains still, just not kingdom scale organized.
These armies get by a whole lot on quality compared to numbers. Their general shtick is to take on forces that vastly outnumber them and still do a lot of damage.