I’m old fashioned; I like cameras to come from people whose strength is optics, not electronics.
The Canon vs Nikon is a holy war, just like iPhone / Android, Windows / Linux / OSX, ZX Spectrum / Commodore 64. It was ever thus.
Bottom line is, both are very, very good and whilst one has slight strengths and weaknesses compared to the other, none are showstoppers. Far more important is personal preference. For me, I found the Canon bodies comfortable and intuitive, and Nikon to be unwieldy and alien, which is why I went Canon. Others would feel the opposite.
What I will say though is, you’re investing in a system. Whether you go Canon or Nikon, be happy with what you’re doing. Do you have friends who might be able to lend you compatible gear?
Molgrips will be along shortly to talk to you about Olympus.