I own this one,
https://egopowerplus.com.au/power-52cm-lawn-mower/ son borrowed it and loved it so we would just keep swapping. Then last year this one
https://egopowerplus.com.au/52-cm-self-propelled-mower-touch-drive-lm21120e-sp/ was on special so I got it and let him keep the old one. But after a while I swapped as his grass is in more normal shape than mine and I found the self propelled not great when you have heaps of corners to go around.
I feel EGO 54V is the right size, the Ryobi's etc. with 36V based on two 18V are probably not good enough, I borrowed one before buying the EGO and was not that impressed. As I have no battery tools I didn't try to buy something to match what I already had.
I now have the EGO lawnmower, Hedge trimmer, whipper snipper and chain saw, all very good.