What are the most popular off-campus apartments? I would like something fairly nice for sophomore year. Also, how do students pay for the apartments, i.e jobs or parents etc?
That’s like asking ‘What is the most popular car at UA?’ It’s all a matter of taste, purpose, and budget. The selection of apartments is pretty substantial and wide-ranging, so what is popular to one person isn’t going to be what someone else wants in an apartment. Have you had a look yet at some places?..and if so, maybe rephrase your question and ask more specifics, and then perhaps those with experience regarding those things can help you. Knowing your budget and how close you want to be to the campus are your two main decisions you’ll need to make. I believe UA Housing has 2 full-time staff to help students with off-campus housing issues, and they have a terrific website: https://offcampushousing.ua.edu/
Similarly, people pay for apartments in a variety of ways: scholarships, wages, parents, 529 plans, other savings, etc. Usually, the apartment complex will ask that the lease be in the name of the undergraduate student, with a parent/guardian co-signing. The student is responsible each month to pay, but payment can come from someone else, of course. The student just needs to make sure it IS paid, on time. 
Good luck with your decisions!
The Gates at Cedar Crest are very nice. One bedrooms will be leasing for fall.
My daughter has lived at East Edge for the past two years. I’d say it’s a pretty popular complex because it’s close to campus, furnished, and relatively new with some nice amenities (albeit amenities my daughter doesn’t use and could easily do without). We liked it because they have studio and one bedroom apartments and D not having a roommate was easier. It’s a good choice for someone who doesn’t have a car, but you’ll pay a premium price. There are newer, amenity-laden complexes, apartments that are close to campus and the strip, apartments with shuttles, apartments that are inexpensive - lots of choices. It’s hard to say which are the best without knowing your criteria.
As for who pays, that runs the gamut as well. In our case, we (parents) pay most of our daughter’s rent, although she has a fellowship that pays a portion of it. We also paid her room and board when she was in the dorms. There are students who pay for it themselves, others who cover it with scholarships, others who pay for a portion of it, or whose grandparents contribute. Different students and families have different priorities, financial situations and ideas about the funding of college and its related costs.