top tier vs middle vs bottom

People's opinions. There is no fact at all involved in rankings.

An unbiased ranking would look at quality of philanthropy events, quality of sisterhood/brotherhood, and academics. But since all of that is also at least somewhat based on opinion (How do we measure the quality of a philanthropy event? Sister-/brotherhood is different for each person, even within the organization. And which one is smarter--the house with a bunch of STEM majors that has a 3.0 GPA or the house with more arts and humanities majors that holds a steady 3.7 GPA?), it's impossible. The rankings are completely arbitrary. The house that one person absolutely hates is the same exact house that someone else is in love with.

Anyways, to answer Op's question, the difference is who you swap with

Listen to active, she gave good advice, the other poster, well her comments speak for themselves. "who you swap with" as basis to pick a sorority is dumb af. You spend a lot of time with the girls in your sorority so you better see girls that you want to be around in your pref choices, don't get fixated on ranking, because after first semester of freshman year you stop caring about that kind of stuff. If you are cute, you will find guys from every frat that want to date you. Look, there a tons of hot guys here, so "who you swap with" is ridiculous. Meeting guys if you are cute and have a decent personality is never a problem.

And you don't really get to pick your house. The sorority picks you. So it doesn't matter about tiers.