I would be cautious with Olympus. Their camera division just got sold and will be going thru major changes.
As far as brands go, I shoot Canon DSLRs, Sony Full frame mirror less, and have a Nikon Z6.
The main thing is glass. With Olympus is that your choices are limited to Oly glass. With the other three you have other manufactures that make lenses at different price points or focal lengths. You will also see more choices in optics being released for mirrorless.
The new Canon mirrorless R5 is being released tomorrow.
