I recently got one to replace the Craftsman that has been a warrior for many years (RWD w/ Honda motor and 1-handle height change - still runs great but have a wheel coming apart and the AWD mechanism is kaput).
After a ton of research, I went with the Ego that come with the 10Ah battery (top of the line). I got that one as much to get the smart/quick charger and the 5-year warranty on the battery as much as anything (the next model down with the 7.5Ah battery has the "regular" charger and a 3 year warranty on the battery - the mowers both have 5 year warranty on everything else). I'm pretty sure the mowers are the same other than those three things (battery Ah, warranty, charger).
The first mow with sorta wet and very tall grass chewed up about 70% of the battery on my 1/4" acre yard. The cut was excellent. The mower is really light, but I did use the self-propelled a fair bit due to some elevation in my yard and to power through the taller grass.
The second mow breezed by with only two bars gone (so only about 40% of the battery used), and with the shorter grass I also forgot to use the self-propelled a lot.
My third mow (and most recent) was pretty wet grass at a regular need-to-mow length, and needed about half the battery with a fair bit of self-propelled use, though I did "forget" it a few times too.
It's super-easy to change height (one handle for all) and easy to set up/store/etc. Build quality seems fine.
My one gripe is the (RWD) self-propulsion isn't a progressive speed (like my old one) - you set the speed with a wheel at the center of the bar and buttons on the grab handles activate it. I'm used to it now, and since the thing is so light I keep failing to use it in situations I definitely would have with my hold one. So a minor thing.
Overall, I'm pretty damn happy with it and would recommend it, other than it is pricey.
I eyeballed the Kobalt 80v pretty hard, since I bought the 80v trimmer and blower in anticipation of getting that mower at some point, but the reviews are very-high or kinda-middling on it, so I went with the Ego which seems to be pretty universally highly-reviewed. As it turns out, my brother-in-law has the 80v Kobalt, and he's been very pleased.