I rotate Rooney, Dzeko, Berba and Villa and they all have good records in front of goal
Last season:
Rooney: 35(10) apps, 27 goals
Dzeko: 36(8) apps, 33 goals
Berba: 17(5) apps, 9 goals (not so good)
Villa: 36(11) apps, 35 goals
So 104 goals between 4 players, not including goals from the rest of the squad, not bad I suppose. Dzeko is an absolute legend though. I play all of them as Complete Strikers, though I think Berba is too much of a lazy sod so I normally change him to Poacher to limit him from having to move around too much!