I run DeWalt at home and the work truck comes with Milwaukee.
I'm happy with both and can't go wrong with either. For the most part stuff is similar but certain tools one is better then other as to balance, feel and small features.This is more with the specialized/less homeowner focused tools.
Once you get the basic starter kit with charger/battery you are good to go and can buy just the stripped tool as needed( cordless circular saws are so much nicer then corded,cordless vacuum is nice for cleaning as you go ) also there are aftermarket battery packs available much cheaper( do your online research prior to buying).
For battery use/long life, heat is the enemy both in use and in charging. I tend to swap out my batteries at the 50% charge mark.I have 4yo batteries still good( used daily in industrial setting)
One plus I like with DeWalt is that when they upgraded their batteries they made an adapter so I can use my older 18V stuff with the new 20V battery packs.
Forgot to add- take a look at cordless tire inflators for each( seeing as you have the 4x4. I have the DeWalt, can't comment on the Milwaukee.