As a guy who is also in his mid-20s, I would advise you to start switching out of the AE/A&F mindset as fast as possible, no matter how good their sales appear to be.
Everlane makes good, inexpensive basic tees and sweaters.
Uniqlo makes good, inexpensive Oxford shirts. I really love their Oxfords.
For polos, I really like Polo's Custom Fit Mesh. The price is quite a bit higher, but the quality is really good.
For jeans, I'd suggest moving into more mid-range stuff like Naked & Famous, or even start making the move into raw denim. I have a pair of N&Fs that I've been wearing for almost 2.5 years now, and I still get compliments on them. Look for jeans that have more classic designs and therefore won't go out of style. No ridiculous pockets, no pre-torn holes; just clean, elegant styles.
I have older pairs of Uniqlo jeans, and they're great (also in the $50 range if I recall), but I'm not sure if the quality has changed since I bought them a few years ago.