I shouldn't say this because it will definitely come back to hunt me, but I'd say we are favorites in every cup competition we're in this season.
The FA Cup is the most difficult one to predict - in the end it's more about luck than anything else. But in relation to the League Cup and the Europa League, I think we'll be well prepared for any match. Cup games are not regular games. For example, I'd be feeling confident facing Leicester in a EL two-legged tie. I wasn't feeling confident at all on Sunday.
That said, the schedule and our players conditions will have a big say in all this. God save Hojbjerg, Son and Kane.
I don't see how we are bigger favorites than Leicester or United in the EL, I would say at best we are co-favourites, which maybe fits the bill for your statement though.
Maybe individually we are favorites over the Manchester teams because we have the harder match but if we face either in the final it would be at best 50/50 if not one of them the favorites.
Don't see how we are in any way the favorites for the FA Cup.