Ranked best to worst:
First serve - Murray, Federer, Nadal, Djokovic.
I put Murray higher because when its working, its much better. However, Federer's is far more consistant.
Second serve - Federer, Nadal, Djokovic, Murray.
Murray's needs alot of work, the other 3 have good second serves.
Return of serve - Murray, Nadal, Djokovic, Federer.
4 of the best ROS players in the history of tennis but i think Murray is the best here by a fair way.
FH - Federer, Nadal, Djokovic, Murray.
Federer miles ahead and Murray well behind.
BH - Murray, Djokovic, Nadal, Federer.
Murray and Djokovic are close here but all 3 miles ahead of Federer.
Slice - Federer, Murray, Nadal, Djokovic. -
Murray and Federer are close here but miles ahead of nadal and Djokovic, Djokovic is awful with it.
Drop shop - Federer, Murray, Djokovic, Nadal.
Federer has sublime drop shots and murrays are inconsistant but better than Djokovic's. Nadal's are awful.
Volleys - Federer, Murray, Nadal, Djokovic.
None of the top 4 are really bad at this imo, all equally good but i tend to see Federer/Murray doing it more.
Overhead - Nadal, Federer, Murray, Djokovic. -
Djokovic is the only bad one here, the other 3 are good and usually pretty consistant with it.
Lob - Murray, Nadal, Federer, Djokovic -
I only really see Murray/Nadal use this alot and its usually pretty effective in forcing a UE or buying some time to get back in the rally but in general i dont think any of the top 4 are paticularly bad at it.
Thats my view.