what are the current reputations of each sorority?

Tiers are based on desireability by pnms. More pnms want to be in the pretty, wealthy, popular groups. That is why you will never see a ranking by National Panhellenic or Elon Panhellenic because these are just preconcieved notions. Keep in mind, the more desirable the sorority, the more girls they get to cut. It's best to go into each day of recruitment with a fresh set of eyes and no expectations based on the schedule of what sororities invite you back.

how tiers are ranked is based entirely on how attractive a sorority is. frats want to hang out with the prettier girls. lets be real, that's pretty much all there is.

I think they're asking about a general run down of the reputation each sorority has. Ex. Zeta's sleep with everyone.

The closest sisterhood on campus is Tri Sigma, least close sisterhood is probably Zeta. Phi Mu is in between.

the higher the tier, the cattier the girls tend to be. not true in every case, but true for the most part.

sigmas are the best. great sisterhood, they're all pretty AND they're close.

Zeta- Girls are known for partying and being hot, but really only one group in each pc is that hot---"star girls". Can be catty and rude, and their president last year was a tyrant.
Phi Mu- Pretty, sweet, southern girls. This pledge class stepped it up and they have made their presence known on campus. Genuine and nice, like to party but are fun to be around.

From a seniors prospective:
AXO - Has been the same way for the last 4 years. Get a bad rap for being the "lowest tier". Most of these girls are nice. Tend to keep to themselves. Never held a lot of campus events or wear their letters.
AOPi - I've heard them referred to as the party sorority that flies under the radar. For a long time they had a squeeky clean girl next door reputation. Now, I hear that they are big time party girls who don't care what others think of them.
Sigma Kappa - Used to be the smart classy reserved girls. Still somewhat reserved or quiet. Seem to be cliquey. Their philanthropy events are the only time I ever see them together as a group, but half of them always look miserable that they are there.
TriDelta - There was a lot of hype about them when I was a freshman. They were competeing with AXiD for that number 4 spot. And were similar to AXiD at that point. Over time, they've had less of a presence on campus, but the girls are super fun and sweet. Easy to get along with and when I do see them out together, they seem to be having a lot of fun.
AXiD - Probably made the biggest change in the last 4 years. Got some really great girls who propelled the sorority forward. Their philanthropy was new to them when I went through recruitment, and I think it really helped them get noticed on campus. Some of the success has gotten to certain girls heads and there is one clique of girls who bring down the sorority as a whole but they are seniors.

Kappa Delta - They have certainly grown themselves into a respectable sorority. They were very new when I was a freshman and relied heavily on their reps from nationals. They have done well establishing themselves, but they still have a lot of work to do. They have terrible relationships with other sororities. I generally avoid them as a group because all they talk about is KD all the time.
Sigma - Generally stayed the same in the last 4 years. They seem to have drama over something every year. Girls always desister/depledge from Sigma. It's not a cult, but it is something that you either buy into or don't. They are a strong sorority.
Zeta - Zeta has gotten more competitive with Phi Mu. They seem to take similar girls. The Zeta's seem to be bigger partiers and more "north east".
Phi Mu - Has stayed in that top spot for the past 4 years. Most of these girls are very sweet and very wealthy and very southern (even though I know they take girls from all over). They did have some drama a few years ago, but they seem to have gotten themselves on the right track.