The Doctor - 5'10", which is actually really tall for a Japanese person, most "tall" people in anime are also below 6 feet too, which I don't blame them if they feel like 6 feet is overshooting it.
Kazuma - 5'5", this will be weird to explain this, but if you take the Kazuma and Momorin sprites together, and completely ignore the pixel height, doesn't it feel like that Kazuma could be taller than Momorin?
With this, it can also be safe to say Momorin is somewhere between 5'2" and 5'3". Itoh is probably also closer to Momorin's height than he is to Kazuma's, so we'll put him there, as well.
Misery/Curly Brace - Now for the more tricky ones, but I'd say these two characters are somewhere between 5'1" and 5'4", around Momorin's height.
Quote/Professor Booster - I'm going to have to agree with Jade here, Quote could actually be shorter than most of the characters, but I do think Booster is closest to his height. So for both of them, they'd fit in the 4'6" - 4'9" range.
Personally, I wouldn't say Quote is ara-ara worthy, tho.
Sue - 4'4 as a human, given she's a pre-teen/early teen, and she knows how to bully Kazuma physically, despite the height disadvantage- STOP IT.
King/Jack/Mahin/Kanpachi/Megane/Zett/Sandaime/Santa/Chako/Sue (Mimiga)/Itoh (Mimiga) - Now here's an interesting one, cuz they're all rabbit people. Rabbits mature much quicker than humans, so Sue should also be taken into account, not to mention Toroko saw Sue as an older sister type of person, further implying (at least to me) that Toroko is a much younger mimiga. Because Mimigas are rabbits, the closest real life rabbit to compare to them is the Flemish giant, which on average grow to 2.5 feet long. So in this case, the adult mimigas and Sue would be 2'6" in height, since they stand on their hind legs.
Toroko/Chie - Because they are younger, we can probably say they're just about 2 feet tall.
Balrog - It's probably a bit unfair to say he's shorter than the Doctor, like in the sprites. Despite his personality, Balrog could be an intimidating force of nature based on his size alone. So Balrog would probably have to be somewhere between 6'6" and 7'0" in height, which hey, it's fitting for him since Quote and Curly sit on top of him in the end.
Jenka - She may be closer to Sue's height, at 4'4".
Ballos - Hmmmmm, how to figure out his height. It's not uncommon for priests to be tall, but given he's as old as Jenka, he in theory could be as tall as Misery and Curly. However, because he is a magic user, and let's be real here, the fact that he has all this rage and magic just building up more and more inside him, it can very well affect his physical height, putting him at a height close to 6 feet. If not, then probably closer to Balrog's height. Quote's shorter stature and speed with the Booster 2.0 would definitely give him the upper hand against the tragic villain who just wants his own life to be taken.