This is straight. I like the beat.
1st dude: He's straight. I think his voice is fine and he has some variety in his flow, but it almost sounds like he's reading from sheet of paper while rapping so he can't really groove with it and get into it or something. If he was doing that, I'd see what he sounds like not doing it, even if it means he only raps 4-8 bars at once then does another take. If he's not doing that, I don't really know what to say. His issue is intangible because his voice is fine, his delivery is varied, and there is emotion behind it but somehow it seems restrained that feels like too much concentration put into something.
2nd dude: I like him. He kinda reminds me of Mac Miller.
3rd dude: Pretty straight. I like his delivery.
Everyone's lyrics seemed good. I'd rank it 2,1, (some space), & 3. Flow wise I like 2,3,(some space) and 1.