The truth is that no other chess site compares to
lichess.org.
Chess.com doesn't even come close. Lichess has a superior interface, is more easily accessible, a better tournament system, has way way way more features, not to mention less lag. Finally, lichess is completely free, with NO ADS. Pretty much any other site, including
Chess.com, requires you to pay a regular fee to have access to many of their basic features. Chess24 has an awful interface. ICC is good, with the strongest player pool of all the sites, but it lacks a lot that lichess has, and isn't as accessible to new users.
Chess.com lags horribly. Plus, most other sites have the completely illogical .1 second cost to premoves, which any respectable bullet player will tell you is not preferable.
Also, some things lichess has that other sites don't: Chess insights, best move arrows, time on the clock by each move made, chess Twitch streams accessible on the main page, instructional features like chess basics, coordinates, and practice, and a video library. I am not sure if other sites have simultaneous exhibitions as readily available, or if they can exceed 125 players if they do. Lichess listens to its player base more than any other site.
The thing is, I can convince you all day that lichess is the best. The best way to find out is to check out other sites as well, and realize it for yourself. So do that if you want to formulate your own opinion. Looking at it objectively, you will no doubt find that no site compares to lichess.