I started out with Canon back in the films day, and was disappointed when Canon changed the mount to EF from the old FD manual focus that was not backward compatible.
However, I stayed with Canon instead of going with Nikon, and bought new EF lenses while owning several EOS bodies film bodies over the years along with old manual focus bodies and 5 FD lenses, because of the superior USM focusing mechanism that wasn't available in Nikon mount.
Optics hasn't improve much in the last 25 years, but the focus mechanism and IS/VR has improved so much that it make your life easier, and greatly help with getting the shots that you may have missed with the old manual focus lenses, or the sluggish screw drive AF.