How would you rank the big 4 on grass against each other? To me grass equalizes the competion against each other more than any other surface. Any of the four have a real chance to beat any of the other 3 without needing to play absolutely perfect to have a chance to win, unlike some other surfaces.
It's razor thin between then:
1. Murray
Pros: best mover on grass, good first serve, very good returner
Cons: weakest forehand, weakest second serve
2. Federer
Pros: Serve, good net game, can take the forehand earliest, strongest surface for his backhand
Cons: slowest mover, weakest defender, high backhands(which happen on today's grass)
3. Djokivic/Nadal (I couldn't decide so they tie for third
Nadal
Pros: can turn rallies into clay court rallies, great forehand for today's grass
Cons: weakest return mostly blocks the ball back, not good at taking any ball early unless its a weaker rally ball
Djokivic
Pros: can take the ball early and up the line on backhand, solid serve, great return
Cons: footing can become unsure on grass, slice and net game.