I am a Dewalt guy (Go Team Yellow), I have a million 20 volt batteries and a mid torque impact that I carry in my storage locker. It shares 1 big battery with my tire inflator. I use the impact on 10" lag bolts instead of hammering tent stakes into rocky soil. Oh, and it works on lugnuts too!
I did carry a Craftsman 20V, but recently upgraded to a Milwaukee 18VFuel to have one power source/tool config that worked across multiple "if needed" tools. I carry a cordless MW sawzall with a plastic container of various blades and a flashlight for more "just in case it is needed" situations.
Any is better than none, though. But you may find more torque and "oomph", better battery performance with some higher end brands.
You should go with whatever battery system you already have or that’s available at your local hardware store. Dewalt, makita, Milwaukee are all about the same in price and performance.
I think all of the brands I listed has a 12v charger available for purchase.
I carry an 18V Makita XWT14Z impact wrench and 100lb torque stick mostly to prevent over torquing a wheel stud but it does also nail the torque value every time. I put a freshly charged battery on each time.
I also carry a 12v milwaukee impact driver in my tent stake box since my stakes are 12” lag bolts.
I don’t carry a charger for either With me.
I have a Craftsman 20v, from Sears, believe it or not, it has done me well. Had it to change out my tires when I went to the track. I also have Milwakee gear, 18v.
I always carried a 1/4" impact for the little tedious stuff. It also works good for running a lug nut down then following behind with a tire iron to snug it.
Brushless motor delivers up to 1,200 ft-lbs of nut busting torque and 750 ft-lbs of fastening torque for effortless tightening and removal of large bolts
Anti-vibration technology reduces user fatigue
Electronic variable-speed control with 3 torque settings for ultimate control
Compare DeWalt 20V
TACKLE WIDE RANGE OF FASTENING APPLICATIONS with 600 ft-lbs of max fastening torque and 800 ft-lbs of max breakaway torque
Here you go if you want to see good test results this channel is awesome. They review with actual scientific testing, not just some shade tree mechanic going chugga chugga with his bias opinion. Lots of different tests. Here is one.
+1 for Milwaukee 1/2". Carry their tire inflator, and a 3/8 cordless air ratchet (which is awesome for door and top removal!). Have bought so many assorted tools from them over the years that I have lots of extra chargers, and always keep one in my tool kit