If you plan to keep it, the Camry. Though, Hyundai quality has improved leaps and bounds except for the engine issues that affected the Alabama-built models. Since the Sonata has flooded rental and Lyft/Uber fleets(from Hertz/Enterprise and Lyft Express Drive/Fair for Uber), you can get a better deal used on the Hyundai - just do some diligent PM(oil, trans and a once-over of the chassis).
Since the Sonata has now replaced the Prius as the de facto car for Uber/Lyft, I've been in my fair share of them. They're not bad, the 2006 model was the turning point for Hyundai but they aren't anything special. The Sonata interior is nicer than the Camry, but it's vice versa to how they feel on the road. I thought the Sonata felt isolated, like an old Lincoln or Caddy.
The new Sonata looks sharp - it was designed at Hyundai-Kia's German studio, it doesn't have that typical Korean me-too look. For a long time, the Koreans imitated the Japanese or had Italdesign or Pininfarina pen out their designs. But then again, Mitsubishi propped up Hyundai and Kia was an arm of Ford via Mazda.
The Camry has been transformed since Toyota has switched the 2018 model to TNGA, their new architecture introduced on the 2016 Prius and C-HR. I was over at The Critic's shop once and I took his rental Camry around the block for a spin. It still feels Toyota restrained, but it feels much better to drive. Dare I say, sporty but not like a Accord?