It depends on your style. Sony has no interest in ergonomics,requiring menu diving for many common on-the-go settings.So pros tend to shy away because Canon and Nikon have catered to those who want full control,and have a camera in their hand for a long time.With most Sony products, they have to be considered short-term replaceable items. Parts for models out of production zoom up and make repairs shockingly expensive. That is one negative feature, parts stocks drop and are not replenished so a 5 year old Sony is essentially a right off. I found that same corporate-wide policy a major headache some time ago. I bought one of their digitial multi-track sound recorder, a PCM-3324 that was $125,000 and the remote control head was another $18,000. As soon as they dropped production, 2 years later the parts were no longer available for the most part and a few common wear items that had been $15 each suddenly were $310. their solution: buy the new PCM-3324HR for only $186,000. My Swiss made Studer tape decks had parts availability for 33 years!! and still worked great.
When I found that my friend's Sony camera just 3 year old was no longer serviceable, I knew they were pulling the same thing with photographers.I don't have the money to replace a $3000 camera every 2 years r less, especially one with an extremely short buffer and over a minute of dead time to clear the buffer before a new shot can be made. Casual shooters don't seem to mind that but that is a non-starter for anyone from a serious hobbyist to pro. Having to carry extra batteries even for short sessions is not what I will tolerate in a camera that also is uncomfortable. I would rather invest in a company which supports me. If the Nikon mirrorless is designed for advanced hobbyists or pros I would be interested in that. If it is not a home run as their first effort,I will upgrade to the D850, the best 35 camera made right now. Otherwise my D800 does more of what I need than any Sony I have seen. If someone can't get the shot with the excellent D500 or D8x0 it is not the camera.