This is gonna be a real battle royal! We have see major increases in all these characters so it's interesting to know just how far their power has come, so what do we know about what each fighter is capable of? Well let's run down them one at a time.
Buu: let's start off with Buu and this new form shall we. Well it certainly without a doubt has more destructive force and more raw power as well as speed, as it kept Goku on his toes when they sparred but keep in mind Goku was not going all out during this fight as he just wanted to test the power of Buu. Overall Buu is no pushover but the full power of this new form is still something unknown to most.
Freiza: I'll just put it out there right now so you guys know what I think. I think Freiza is the odds on favorite for this fight between the four fighters, even more so now that he seems to have refined his golden form making him more dangerous then ever. With this I would put Freiza about on par with Goku in terms of speed. Maybe slightly inferior in terms of strength but still Freiza may body the other three fighters here with only mild difficulty at best.
Gohan: My man Gohan! Well after seeing how he has been performing in the Tournament of Power so far and his training with Piccolo beforehand, I would say Gohan has either the third or even second best chance at winning this fight. What drags him down however is that no matter how powerful Gohan has become he still is nowhere near as skilled as some of his allies and enemies. That being said he's not totally clueless he's just more straightforward then most others would think.
Android 17: last but certainly not least is 17. 17 has one advantage over the other three that makes me able to hang in there no matter what he faces, yup you guessed it I'm talking about the nigh-infinite stamina enhancement of his cybernetics. With this 17 can tease the others into burning energy and try to come out with minimum damage to try n go for killing blows. However the hard part is actually doing this for him, no I know he sparred with Blue Goku but again like with what I said about Buu he was holding back. And yes I'm aware 17 was holding back as well, that being said even with his energy advantage I don't like his chances all that much.
Well you guys decide who takes the win here. My vote is either on mostly Freiza and maybe a little bit of Gohan.