Rovers have been beaten by both clubs in recent weeks.
"It is between United and Chelsea for the title," said Blackburn's captain. "I think they have got the experience and the players. But I'm going to throw it out there and pick Chelsea - and I'm sorry to say that because I'm a big fan of United.
"But I think Chelsea have got a lot of game-winners and a lot of players who have the ability to change games in the blink of an eye.
"I'd love to see United do it because I like what they do here. But it's logical that when you lose the world's best player it is going to affect your team. Ronaldo is irreplaceable."