agassi was more reliable because he hit his ball pretty much the same way all the time.
but ive never seen a player handle pace better than federer.
federer hits with more spin, and thus will mishit sometimes. But i dont think he mishits at a rate higher than his peers. Agassi probably did not hit the frame as much as fed but this has so much to do with their technique and the angle of the racquet.
Federer just does more with the ball than andre and takes more risks.
But in terms of hitting a flat ball...a train was more reliable.