I have the EGO 56V and the in-laws have a Stihl. Both cut better than expected for a battery saw.
EGO-heavier than the Stihl but has a larger gauge bar and chain.
Stihl-lightweight but uses a small .043 chain.
I've cut some large, 18-20" oaks that fell in the road with my EGO. No problems at all. We were already invested in the EGO platform and that's what helped my decision. I have two of their blowers, hedge trimmer, chainsaw and the split shaft power head system with pole saw, hedge trimmers and weed eater.
I really like having a battery saw to throw on the tractor when mowing roads. Don't have to carry fuel and it's quick to jump off to cut a limb etc without fighting a gas saw to crank.
