I’m just copying a reply I made a year ago to a similar question, since it seems this question comes up pretty often for the newly admitted students. If you have more questions, just let me know. Note that the below doesn’t consider the New College House since it opens this fall.
"If you haven’t already seen this, look at the brochure here: http://www.collegehouses.upenn.edu/sites/www.collegehouses.upenn.edu/files/College_House_Brochure_2015-2016.pdf
For recommendations, it really depends. Many incoming freshman put the quad houses (Riepe, Fisher, and Ware) as their top 3 choices, but the quad is not for everyone.
If you’re looking to live in the quad, just put the 3 houses as your top 3 choices with your room type preference and hope you get into one of them. I wouldn’t put too much thought into ordering them. They’re all pretty similar in terms of rooms and the experience of living in the quad is basically the same for all 3.
If you are looking for a non-quad single, then Stouffer is a good option. It’s a quieter atmosphere than the quad, but it also has the advantage of being the closest dorm to the quad (it’s right next to it), so if you ever want to hang out with friends in the quad, it’s convenient. On the other hand, dorms like Kings Court, Gregory, and Hill are much further away from the quad. Stouffer itself is also mostly freshman, so you will also have the chance to make many friends around your hall.
If you want a non-quad double, then applying to Freshman Experience in Harrison can be a good option. You would get to live in an apartment-style suite with a kitchen, private bath, and common room. If you’re looking for a non-quad double that isn’t in a high rise, then you can choose from Hill, Kings Court, and Stouffer. Out of the three, Stouffer has the most convenient location for a freshman, but there are only a few doubles in Stouffer.
If you want a non-quad triple, I’d recommend Mayer Hall. Mayer is probably the nicest dorm on campus, and the rooms are the largest on campus (definitely bigger than the high rises). Even with three people living in one room, you’d all have plenty of space, plus your own common room, bathroom and kitchen. Also, Mayer is organized such that all the freshman live on the 5th and 6th floors, so you won’t be isolated from other freshman in any way.
There are also some other room types that I haven’t mentioned (see page 57 for a full outline of all room possibilities).
Hope this helps. Also consider residential programs in different houses (I mentioned Freshman Experience, but there are many others)."