sorority comments

Ranks are based on looks and which fraternities you exchange with. Some girls will say personality, location, etc but those don't matter

Basically that's it. Upper tier houses (Kappa, PiPhi, DG) have the richest girls, most are white, attractive and have confidence/personalities. They party with the top tier frats and are highly competitive to get a bid to.
Upper mid houses (SK, ChiO and APhi) still party with the top frats. Most are highly outgoing, like to party and are attractive. These houses are less rich and white though and have worse locations than the top houses.
Lower mid houses (ADPi, AOPi and AXO) are still full of mostly pretty girls. They tend to be less of the party girl type, however, and lot of them are more reserved and not as social as the higher house girls. AOPi and AXO have really bad locations and don't necessarily party with top frats. ADPi is a bit better in that aspect, but has recently become less attractive, more nerdy.
The bottom houses (Tridelta, GPhi and Theta) tend to have less attractive girls (still way above the average Berkeley girl) than other houses don't party with higher frats.

Kappa
Pi Phi / DG
SK
APhi /ChiO
ADPi/AOPi
AXO
DDD
GPhi / Theta

Most accurate going into fall 2012 is what the person below posted:

Top:
Kappa
PiPhi, DG

Upper Middle
SK
APhi, ChiO

Lower Middle:
ADPi, AOPi
AXO

Bottom:
DDD
GPhi, Theta

Here are the rankings from a top frat's perspective:

Kappa
PiPhi
DG

SK/Aphi
Chi O/Adpi

The rest are not worth joining, if you aren't able to get a bid at one of the mentioned 7, you should drop. I personally would drop if I wasn't in the top 3 because the 4-7 are wannabes for the most part

All that matters as to who you exchange with are general tiers. If you really care that much about exchanging with "top frats" (which doesn't necessarily mean "hotter" guys, since frats don't recruit based on looks) you should try for the highest tier you can get. Within a tier, choose the house you like best and click with the most.

Top:
Kappa, PiPhi, DG

Upper Mid:
SK, ChiO, APhi

Lower Mid:
ADPi (slightly higher at the moment)
AOPi, AXO

Bottom:
DDD (still slightly higher than the other 2 at the moment)
GPhi, Theta

Although be aware of houses rising and falling year after year.

It's hard to believe that "top frat" guys come on here a lot to leave there comments...
Although if you really are in a "top frat" I can tell you the only reason why YOU think that some houses are not "worth it" is because you don't party with them or take the time to get to know some of the girls. That's ok. Other frats who exchange withem owner ranked sororities certainly don't think that these houses aren't worth being in...Not everyone joins a sorority to party with the top tier frats!!! All houses have equal opportunities for exchanging, it just varies with whom they do.

Frats absolutely give bids based on looks. If you aren't good looking it's very difficult to get a bid to a top house

Ok, so there's all this talk about houses "worth" joining or not. The truth is, all houses are worth joining and you can have the time of your life in each house, depending on what you make of the experience. I've known girls who were absolutely miserable in "top tier" houses and ones who wouldn't want to be anywhere else than in their "bottom tier" house. So remember, houses "worth joining" depends on the individual girl.

Yes, if your goal is to get into a house that exchanges with top tier, mostly campus-disaffiliated frats, the only houses "worth" joining might be the top tier. But if you value sisterhood, getting to know girls who are like youths who you don't have to change for, you might want to look elsewhere too.