I think this year is a bit of a free-for-all.
At the moment, I'd edge toward Juventus as I think they are the probably the most 'improved' team in terms of how good I think their transfer business has been, but that isn't always the deciding factor (it probably even rarely is).
Man City could be facing a tough start to this campaign (by their high standards), but they will comfortably progress to the knockout rounds and then there's a good chance Laporte will be back when those games start in February.
Liverpool are a juggernaut but they're only ever one or two big injuries away from looking a bit short IMO - but, it doesn't seem to happen at the moment which is testament to their fitness levels and medical team (and maybe a dash of luck). They'll be in the mix, but we know how hard it is to retain the Champion's League, let alone get to two or three finals in a row. I think they will fall short, especially if they are still ahead in the title race come February, but it'd be stupid for anyone to write them off making a third consecutive final.
At the moment, I fancy Juventus or Man City to win the Champion's League, with Liverpool perhaps winning the Premier League and focusing slightly more on that competition (not through means of team selection, but just a mental effect on their players if they are in a strong PL position next year). I just think three finals in a row is a monumental ask, but maybe they'll do it.. Perhaps a surprising bit of amazing January business will get them that squad player who covers them well enough?
Juventus > Man City > Liverpool > Atletico