I have an account in Lichess and Chess.com. And my experience is that there are much better players in Chess.com. Probably because Chess.com has more chess players and people who pay to play chess, spend more time and effort to getting better at chess.
is premium worth it?

No one can decide but you if it's worth it. Do you have the time and motivation to take advantage of premium features? And of course, to cite an extreme example, can you afford it or is paying the rent each month a bit of a crisis? I'm not rich by any means but I think the $100 a year I pay for diamond is well worth it. My rating doesn't reflect it because I'm old, but I do 5 or 10 lessons almost every day. Diamond is the only level that lets you do that many.
For anyone that has signed up, do you think it’s worth it and if so what level would you recommend?
Is there a lot of difference to Lichess?