i say depends on use. mostly bench shooting? 2 stage.. or a little of everything? single stage.
I have been a silent witness
to all of America's finest hours.
But my finest hour comes
when I am torn into strips and used as bandages
for my wounded comrades on the battlefield,
When I fly at half-mast to honor my soldiers,
Or when I lie in the trembling arms
of a grieving mother
at the graveside of her fallen son.
I have a Timney 4lb in one of my ARs and a Timney 3lb in the other (both single stage). I love them both and they are very easy to install!
I used an RRA with a 2 stage trigger before I knew much about ARs and didn't even realize it was a 2 stage. I'd have to spend some quality time with one again to see if something I'd prefer that over single stage but I doubt I would for my uses.
I don't believe it matters as long as you are used to it.
A good trigger is a good trigger, be it single or 2 stage. It will come down to your preference.
FWIW, I'd talk to a gunsmith about a trigger job before I spent money on a drop in. YMMV.
Greg USAF Retired NRA Life Member "If you put the federal government in charge of the Sahara Desert, in 5 years there'd be a shortage of sand." Milton Friedman