The 5200 is a gem. It's a cult among Atari owners. And it has a ton of great games that are configured for the 5200 controllers (space dungeon, centipede, star raiders, countermeasure etc). The latest tempest, adventure2, and pacman arcade are amazing games.
To avoid hardware issues, get a working 2 port.
Buy sticks that work. If you spend some time to learn how to rebuild them, you can easily do them yourself. There are people that can refurbish yours. My gold dot flex upgraded sticks are going over 10+ yrs.
The 5200 controllers are my fav in that era. Better than coleco, intellivision, and 2600 easily for me. They just need to be maintained and understood.