There is no such thing as a "best" platform.
I own or have owned power tools from most makers. They all have their strengths and weaknesses. You will always be compromising something if you stick with only one brand.
I own and daily use Metabo and Milwaukee m12 and m18 in the shop. At home I have Bosch. My dad has DeWalt. I used to use Makita as my primary. I have also used Snap-on daily in the past.
I don't have any issue with multiple battery platforms. Some tools simply aren't available in other brands, or aren't very good if they are. I think I have 4 or 5 brands of chargers on my charging shelf.
So far in my experience, Metabo makes the best tools for a welding shop. Bar none. Their cordless drills, impacts, hammer drills and grinders get daily use in my shop and they are leaps and bounds better than the nicest Milwaukee or similar. Milwaukee makes a lot of tools geared toward the construction trades that just aren't available in other brands. And they are very nice. But not available on the Metabo platform. So I buy the Milwaukee. Bosch was running a promo for a drill, impact, sawzall, and flashlight in a bag for a steal a few years ago. So I bought it for my home toolbox, despite having Makita and Metabo at work.
Forget the idea that these are legacy tools. You won't be handing these down to your grandkids. Cordless tools are disposable. They last about 10 years. Even the best power tools on the planet have a useable life. We also are making leaps and bounds in cordless tech every year. I remember when Makita was the absolute hotness with their Ni-Mh batteries back in the 90's. The long skinny ones. They were the bomb then. Absolutely un-useable by today's standards, even if the batteries would hold a charge.
Buy what you need to do your work. Use it for as long as you feel is practical. When the next best thing comes along and you can justify an upgrade, do it. I think some guys put more thought into "what platform is best for me" than they do with what woman to marry. I don't understand this. When I needed a new impact wrench, I bought the one with the best reviews and that happened to be a Milwaukee. I had Makita, SO, DeWalt, and Metabo at that time. But the Milwaukee is better. So I bought that one. And now I can buy more Milwaukee tools and add to that fleet.
If you buy a tool you don't like, sell it on facebook or whatever and get a different one. ANY brand made today is 10x better than the NiCad stuff of the 90's. And that stuff cost 2 or 3x as much.