Cell phones compatible with at&t

Does anyone have suggestions for cell phones that go with at&t? Mine has had it and I'm asking for one for my birthday but don't know what's out there. Do you have one you really like?
TIA

i have an htc one. it's not the newest phone, but it's inexpensive and i love it. Anything that has an android market imo is best. They have the most apps.

blackberry curves

An old version of something is fine.. especially because of how expensive new ones are! Think there would be any on like, craigslist or ebay?

thank you both i will look into those
I am pretty clueless about current cell phone trends lol

theyre absolutely loads on ebay x