- latest engine, with webassembly or cloud mode
- "learn from your mistakes" mode where when there is a drop in valuation of the position, you're given the position and are asked to find a better move ; you can also find bad moves from the opponent which is interesting to help spot mistakes faster
Also puzzles are great if you have an account (free), I find the puzzles of great quality, they really match your level and once you get better at solving the common tactics, they look more and more like small studies where you might only get positionnal advantage sometimes (instead of the classic "win material / mate in X moves" type of problem which is a bit redundant after a while).
I don't know how they generate puzzles but it seems that a lot of them are from games actually played on the site where only one line seems to give an advantage. I think it's amazing that they do that. High quality puzzles from real games.
For a long time, I encouraged my IRL friends to set up their personal newsletter and write once or twice a month so I can subscribe to. Quite similar to this social media idea.
I think it's a very good way of getting updates from people I care about. Social media is just too noisy.
The plan hasn't been working very well unfortunately.
(I use lichess analysis frequently and haven't used chess.com much)