I think personally both are great, and both are great for the community; in different ways. Chess.com is a bit “pay pay pay please” for my taste but they do host a ton of events and sponsor many things. The interface is quite good and the cheating control is quite good.

Lichess is better though, in my view. It is much more open, the interface is lightyears better in my view and the study / analysis tools are better too. However, reporting is much more cumbersome, because on mobile for example, you have to get a share link to the game, then use the website to report and actually explain in prose why you suspect foul play, even though simple click reports should be at least partially useful for trend analysis. However, their actual detection seems good too.

All told, both are great ways to play chess, both use good rating systems (Glicko 1 and 2), both control cheating pretty well, and both suck the life out of me one bullet game at a time.