I am life-long Chevy guy. My family currently has 4 vehicles, three Chevy with V8 and the RV with Ford V10. My wife and I have owned three RVs since 1996, the first two were Chevy based and our current is a 2019 Thor 23' Class C on Ford chassis we bought new in April 2019. So I am not exclusively brand-loyal but I definitely lean Chevy.
That being said, our Ford V-10 based class C has been fantastic in every way. I am happy to go on and on about how much we love this rig or answer any specific comparison questions if you like. But for now I would like my #1 takeaway for you to be: please do not focus on brand for the sake of brand.
I know Ford went through a pretty major revision in 2016, so the 2016+ rigs are vastly different than the 2016- rigs. Not sure when (if) Chevy did a similar update in their van chassis, but be sure to compare apples to apples. A 2017 E350 would be vastly different than a 2015 E350, for example. Have fun in your search!