Liverpool are currently the top contender for the championship. I assume most people share the same opinion as me. 
They are currently the only team without a loss and winning 6 out of 6 games so far.
However it is still too early to be very confident about something of course. This is only league phase. Even the top teams not performing very well these days can start playing much more differently later on. Such as Real Madrid.
Besides I believe Barcelona also have a quite big potential here this time. Hansi Flick's system works very well in the Champions League too as far as I can see.
Do not look now to determine it, because we know this is only in the early phase and not yet to the next round even though Liverpool has a series of wins without losing they will still continue to fight to the next round. They are currently the only team without a loss and winning 6 out of 6 games so far.However it is still too early to be very confident about something of course. This is only league phase. Even the top teams not performing very well these days can start playing much more differently later on. Such as Real Madrid.
Besides I believe Barcelona also have a quite big potential here this time. Hansi Flick's system works very well in the Champions League too as far as I can see.
Liverpool are experiencing poor results in the Premier League, hoping this does not affect their play in the Champion League and it is certain that in this phase Liverpool will qualify.
Now in the next phase, we don't know which team will meet so it will be a tough challenge again.
I don’t think it’s possible to compare a team's performance in the Champions League and Premier League, because these two competitions are totally different. Many teams do not have the strength to keep their consistency in two competitions, and I see that in Liverpool. I think they can’t manage to be at the top of both leagues till the end of the season; that is why their performance is declining from now on,
although the Champions League is a tough competition that has many tough teams that may be challenging to them. But even with that, I don’t think they will give up on this two competitions. They must be able to win one of them at the end of the season, especially the Champions League.