I assume that you mean Liverpool are the strongest among all the teams which have qualified for the current round. It is your claim of course but I also suppose that they are really one of the strongest and closest teams to the Champions League title now certainly. But they should never lose their current level of discipline. Klopp should get them ready very well for their each game.
It's complicated to choose which is the strongest team.
I see some possible candidates but I can't say which one is better than the other:
Bayern are in first position, they remember a lot what we saw in the 2019/20 season... many chances to win.
Liverpool are not far behind, they have been undefeated since April and have a real chance of taking first place in the rankings.
City is another team that I respect, they are group A leaders and they also show an excellent result.
It's been a long time before games resumed and these performances could change, only time will tell.