Tevez and Rooney are about equal. Hell a lot of United fans thought Tevez had eclipsed Rooney after last year. Rooney basically went missing for 8 months.
Tevez didn't really have a team built around him like Rooney does until he came to City, in top flight at least. That's when he became prolific.
Ability wise, Rooney just doesn't have the ability to do something like these
http://www.soccerclips.net/videos/man-city-2-1-wolves-tevez
http://www.soccerclips.net/videos/man-city-3-0-stoke-tevez1
Rooney's passing and attitude are better than Tevez, though.
David Silva is comfortably better than Rooney, with even some United fans admitting it. Virtually every neutral thinks this, English announcers even say it.