I've got a Milwaukee battery snipper and I love it. One 8ah battery covers the 1/2 hour or so of whacking on my yard.
I've got the tri-blade attachment for hacking bush trail too. 2" trees are doable with 2 or 3 hacks into it. Stands up to abuse well so far. Had it for 3 years now.

depends on how much you have to do

I did a Rigid battery last year , it works well , I get about 20 minutes of run time on a battery

it is quiet so when I want to run it before or after a time a person should stop running power equipment to be kind to the neighbors.

easy to pick up do 5-10 minutes of trimming then put it down

I would go with whatever battery platform you run your other tools on .

if you spend more than 20 minutes with the string trimmer , gas

I bought a new Stihl last summer and I am less than impressed. The thing runs HOT. 3-4 min and the exhaust is so hot its burning my elbow. I took it back to the dealer and the adjusted the carb but man it still sucks. I haven't used a Milwaukee battery one but my son bought the chain saw and I have been really impressed with it. So far it has worked great trimming limbs and stuff.