Owned all three. Provided condition is similar in all three:
91/30 has longer barrel and longer sight radius, so naturally shoots better. I put a PU scope on mine, but have also had to devise a method for moving through dense stuff with it... Have a cloth muzzle cover for fear of accidentally stuffing it full of pine needles or dirt while entangled in a clump of pine trees.
M38 is quite handy. Personally I prefer them to M44's... just something about how they feel... Mine was fairly accurate once I figured out where it shot. Mine also had g-vg bore and wasn't counterbored though, so that's part of it. Haven't heard much about how the counterbored guns shoot, but unless the bore's buggered all the way down, and not just where it was counterbored I can't see it being a really big problem.
M44. Well, it's cool, but just doesn't do it for me. It's probably psychological, but it just feels heavier and unbalanced to me. If you dropped the bayo that'd mostly alleviate it though... probably. I heard all sorts of stuff about 91/30's being sighted with bayos affixed too, as the usual practice was supposedly to keep them mounted at all times unless for storage or transport, but most I've seen shoot pretty much the same. I don't know for sure, but I don't think the bayo will be the issue.
M44's are the best price right now, considering you're looking for a carbine, so why not give'er a try? Find one for cheap and if you don't like it you can always sell it to someone else.