Im dumping the 2019 Kia Optima S 68,000 miles on it and too many problems
Waht do you suggets I buy in a 4 door sedan either new or a few years old.
Brand new is best in this market since you said few years old and in this case prices are close to new or even higher. Depends on if you want hybrid or not and what size. But I like the Honda Accord; get either the 2.0T or hybrid that doesn't have turbo. Camry is good too either hybrid or gasoline only. If you want something smaller then Civic or Corolla; Corolla has hybrid version too while Civic has hatchback and manual options. Prius or Prius Prime is good too if gas mileage is an important factor. At the end it comes to personal preferences and what size you need; but quality and reliability these are all good.
Toyota or Honda
Look at Toyota Avalon or Camry. I would pass on the Hondas if you care about longevity and overall reliability - just more maintenance to be on top of with the Hondas and I am not impressed with their engineering decisions over the past many years. Personally, I would never buy a modern Honda.