Optic is, IMO, the best NA team atm. Liquid, C9 and CLG all lack consistency and honestly I can not see a world in which any of the three beat Astralis in a BO1 and Tempo Storm on two BO3's on LAN not too long after that (maybe liquid if they didn't choke). I could be overhyping OG though.
Then, Liquid. They seem to be the most consistent team of the three mentioned before and the one who puts up most of a fight. With peacemaker on the team, they've potential to actually be contenders for some international LANs.
No idea about C9/CLG. I just can't see C9 as a consistent team anymore and I'm going to need some retraining if that's to change anytime soon. CLG, they seemed like the best team coming out of Columbus but now I just don't know what to think of them.