If by "better than both" you were judging their peak game, Murray can't touch Safin. Safin and Hewitt had to deal with prime Fed. Hewitt was clealy hurt by that, if not he would have a few more slams or TMC. They also played when surfaces were different.
Yeah, Murray played prime Federer as well. The difference is that he actually earned a few wins, despite being a shadow of the player he is now.
Let's be clear. Federer's decline has been overstated. People were arguing that he was past his peak by the age of 25, simply because he started to lose because the top players improved.
And don't even get me started on how overrated Safin is.