best fraternities

In my opinion

"Top Tier"
Phi Kappa Tau
Acacia
Phi Kappa Psi
Sigma Phi Epsilon

"Middle Tier"
Sigma Pi
Sigma Alpha Epsilon
Alpha Epsilon Pi
Beta Theta Pi
Phi Delta Theta

"Bottom Tier"
Lambda Chi Alpha
Theta Chi
Pi Kappa Phi
Phi Kappa Theta
Delta Upsilon

My opinion is based on what I have observed, and my personal like and dislike of certain fraternities, so its definitely biased.

I would say that Phi Tau, Phi Kap, and DU have some of the best brotherhoods.
All of the fraternities have pretty good social calendars, with the exception of the ones that I put as bottom tier.

I don't really think being in a top tier house is that important at OU.

Hopefully some other people will reply to you so you can get more opinions and a more accurate idea of OU's greek life!

Top Tier:
Phi Tau
ACACIA
Sigma Pi
Lambda Chi
Phi Psi

Middle Tier:
Phi Kap
Phi Delt
SAE
Beta

Bottom Tier:
Delta Upsilon
AEPi
Theta Chi

I, along with surely anyone else in the OU greek system, would strongly recommend you to check out at least a solid handful of chapters both before and at the beginning of rush week. After you spend a little time at a few fraternity houses/rush events you should have a good idea of where you want to spend your next couple years as a Bobcat. Good luck!

PS, good choice on the transfer. Transferring to OU was the best decision I've ever made. Enjoy.

The guy who posted above me is obviously a Lambda Chi

Don't get caught up in the "tier" system. This just makes you join for the wrong reasons. I know it can be hard to find the right chapter because you basically have to know someone in one to check it out. One of our members checked out at least five different chapters before he found us. If you see a guy around campus wearing letters just ask them about rushing. Honestly, if they care at all about their chapter they won't mind.