The challenge this season is going to be between Chelsea and Manchester United: they are the best two teams of the league, the most well equipped to win the English Premier League. If I would have to bet today i would pick Chelsea as I do not think they will be able to win the Champions League again. But as for the EPL, they are certainly the best. They were good last year and now they are even better.
I wouldn't bet at the very beginning of the season that they could win the Champions League. In the English Championship, they may be able to compete for gold, with grief in half... But here's the Champions League, given that this season there will be a powerful PSG and several other clubs will be difficult to win. I think Chelsea will fly out at the 1/8 or 1/4 stage. So far, they can't show football at a very high level.