Need to differentiate between sharpness and maximum sharpness.
The maximum sharpness is obtained at two stops less than the maximum value (for example if the max is f/2.8, the maximum sharpness of the lens will be at f/5.6).
But this is not all, can improve the sharpness in: using a tripod, a trigger or the self timer, by rising the mirror of the reflex system.
Finally, it is certain that the budget given for buying the camera and the lenses are important. Lenses are even more important than the camera itself.
Might be interesting to know that with the Leica M9, its possible to take a picture at a 15 of a second without tripod. The weight and the shape of the camera make it easy. I could make it with both of the 35 and 75mm lenses. With a reflex, speed should be 40 and 80 of a second minimum to make sure the image is sharp.