here we go

Phi/Chi O
KKG/AXO
THETA/ZETA
KD/SK/PI PHI/G PHI
AXID/DG
SDT/AOII

It's very clear that Phi and Chi O have the prettiest girls in their sorority. They also have very good relationships with every fraternity on campus.

KKG and AXO both are very different houses, and have different personalities but I personally think they are both on the same level look wise. (but again both very different types of girls AXO hippie look KKG preppy rich look)

THETA and ZETA again have pretty girls in their house, but also very different types of personalities within these two. Theta seems to be the more classier sorority out of the two.

Now the middle tier houses - KD, SK, PI PHI, and GPHI. They all generally have the same kinds of girls in these houses. They all have some REALLY pretty ones, they also have some randoms. They all kind of hang out with the same fraternities.

AXID and DG have pretty girls, but are at the bottom of the list. This is personally as far as I would go when trying to pick a house. If you didn't get any house up until these two.. then try for one of these.. and don't go down any further.