What's a better car brand, Hyundai or Nissan? Which one is more reliable, better quality?

Based on reviews Hyundai (Sonatas) are better than Nissan (Altima)

Assuming you're referring to brand new 2020 model year vehicles, I'd take a Hyundai over Nissan.

Nissans' used to be great cars up until about 20 years ago or so but their quality has diminished over the years.

Sonata is better in reliability and more spacious. Don't get a Nissan until they no longer use their CVT transmissions.

I'm certain that Hyundai is a far better brand than Nissan these days.  Check Consumer Reports.  Also, the Sonata is a midsize and the Versa is a subcompact.  I'm sure the Sonata is much better.

Both will be good for 5 years when new.  Everything after that is a roll of the dice.  Get a Toyota if you want to drive the car until the wheels fall off.

I'd avoid Nissan just based on the model years after 1999 being far less reliable than their earlier models. That said, Hyundai still requires a 3K mile oil change to maintain your 10 year 100K miles warranty. Neighbor bought a used Hyundai and they replaced the entire engine about three years later under warranty (for free) since they had all of the records showing service. You will not get the same deal with a Nissan.