The odds for the Premier League winner are already here:

Liverpool - 2.88
Arsenal - 3.25
Manchester City - 3.50

It is totally normal to favour Liverpool the most. They made it for the trophy even without much of a signing last season. Now they are even getting stronger with many transfers.

I don't know whether it is fair to favour Arsenal more than Manchester City yet but they must be referring to last season results only. Arsenal still need a centre-forward transfer in my opinion.