Once you have a set of good objective lenses and a sub-stage condenser, you can start to look at making the microscope as pleasant to use as possible.
Low placed coaxial fine and coarse focus knobs make focusing much more convenient. The placement down low near the table or desk means that your arm can rest comfortably on the table while reaching the controls.
A mechanical stage is also quite nice. If it also has low coaxial controls, your hands can stay on the table for both focusing and moving the slide around.
If you are going to be looking into eyepieces instead of looking at a computer screen or video screen, then a nice binocular head will let you relax both eyes and get a better view. Having the eyepieces angled at 30 degrees makes them more comfortable than being straight up and down, and is often preferred to the other common option, which is 45 degrees.
The light source might be halogen, or you might have LED lighting, which frees you from having a cord plugged into the wall. Now you won't trip over the cord and pull the microscope onto the floor, and you have more choices of where to work. You can even take the microscope out in the field.