Honestly, I'm over the Hollister/A&F phase, but I still love American Eagle.
Quality, they are pretty much all the same, except for Aeropostale. Poor quality. Abercrombie's quality is slightly better than all of them, but it is also more pricey than all of them. I love Hollister jeans and I love AE tops.
Hollister and A&F have really similar styles when it comes to tops and jeans (they will always have babydoll tank tops, tight-fitting polos, ripped jeans, sinny jeans, the expensive faux-fur hoodies, etc.) and AE has really basic clothes, but they often have things that stand out.
Overall:
Hollister: 9/10 (I love their jeans)
A&F: 8/10 (too expensive; too tight)
AE: 9/10 (Style could be a bit better)
Aero: 7/10 (Ugly fit, semi-ugly styles, but they are very cheap)
I currently shop most often at AE, Old Navy, Target, Nordstrom, and some vintage stores.