The one complaint about the Prusa i3 is that the supplied filament holder is a bit too simplistic. When using filament spools of different widths, you need to move around one of the posts, which is quite annoying. I simply cut a 15cm part off a PVC pipe that I had lying around. You still need to bend the posts to remove the pipe, but at least they can be kept at the same distance for all spool widths. With a long enough piece of pipe, you can even fit two spools for quick filament changes.
There are, however, several nice 3D printed solutions. I quite like the looks of this one.
Another complaint about the Prusa i3 is that it is a bit noisy. There is a silent mode (which some people claim may lead to issues with print quality), but you may also benefit from vibration dampers.
A filament guide ensures that you get good filament supply to the extruder. I printed this simple design, and it seems to do the job nicely.