Murray(on fast hard), Nadal on clay or slow hard
murray on hard
nadal on everything else
Love how people forget how good Federer's serve used to be before this year. Not to mention his movement. Sure maybe he was not as fast as Nadal but his anticipation on court was at another level. At his peak his movement used to look like he was gliding around the court. One moment he would be at one end of the court, a blink of an eye later he is on the other side hitting a ball back that most would think he can't even get to.
Anyways I just realized this is totally off topic as the title does not even ask for movement. It just asks for serve and groundstrokes.
4 Nadal (I feel Nadal even though he does not have a great serve and agressive returners like nalbandian and murray can really punish it, he back up his serve very well with his amazing groundstrokes.)
2 Federer (well he would not be #2 right now with his current error-fest mode but at his peak)
3 Djokovic (groundies can be extremely good when he is on)
4 Murray (way too defensive at times, very little risk so I feel that if someone like Djokovic or Federer's game is ON their groundies are better. Sure Murray can be very good with his groundstrokes aggressively but that doesn't mean much coz so can someone like Monfils. But there is a reason why they play defensive with low risk most of the time.)