Hall of Fame
You talk as though Serve is an illegitimate shot in tennis.Putting Safin aside, nalbandian vs fed is a hard one.
Fed is probably the greatest player ever overall, but nalbandian is, to me, up on Mt.Olympus with him. In terms of touch, and court awareness, shot making, he's as good and I would say better than fed.
Like the triangle of combustion though, all the elements have to be there to get flame, and nalbandian was missing self belief deep down. He couldn't find a way to close big matches down, because it wasn't a plausible reality to do so in his mind deep down, so he'd flounder. Fitness is also an obvious one too.
But even with these issues, if you took both at their prime but took away fedbots serve +1, and gave him a serve like Nalbandian's, I'd pick nalbandian to win.