I really need to pull the trigger on one. I'd just prefer to keep all the same battery ecosystem (MIlwaukee) and their version is double the price of an Ego WITH batteries.
I'd keep an eye out for sales on the EGO. It seems like the way to go. I specifically did NOT go with the Milwaukee or other similar unit because I don't think the M18 or similar platform makes sense for mowers and other large equipment.
I wanted to stay with one battery type and then realized it wasn't the most ideal once going between small/medium/large type devices. Specifically i went in a small/medium/large:
Milwaukee M12 - Brushless Drill/Driver/Jigsaw/Oscillating Saw. Heavy-Duty tools, smaller/easier to use than the larger M18 plus cost effective. The Drill/Driver is fantastic and in constant use as is the Oscillating Saw. Oscillating Saw is one of those things that I can't believe I lived without. Milwaukee Jigsaw is not great and overpriced. If I was already in on M18 or so I'd happily stay with M18.
Ryobi 18V - Started picking these up for the larger/heavier duty stuff than the M12 where I may not use them as often and am not looking to go Milwaukee M18 due to cost. For instance I took advantage of the sales on the 1/2" Impact gun for lug nuts and such and it's *way* cheaper than the Milwaukee. I'm not going to use it as often. And now can jump into sales on other things like the disc sander that's showing up today or the 7.5" circular saw I'm going to order...
Ego 40V - Mower/Chainsaw/Pole Saw/Weed-Wacker/Blower. It makes way more sense for these to be an Ego battery. They're way larger than an M18 battery. The Milwaukee mower needs I believe a PAIR of 18V/12AH batteries which isn't something you're going to use with a typical drill/impact/etc so there's not much benefit in sticking with Milwaukee here unless you're stealing batteries from your jobsite. The Milwaukee mower is literally twice the price of an Ego and I don't see any benefit.
I picked up the Ego stuff on sale piece by piece, so now have 5 items, 4 batteries of varying sizes. The smallest one, for the weed wacker, is probably bigger than any normal power tool battery.