Blackhawk vs. GP100 Trigger

Which has the better out-of-the-box single action trigger, a Blackhawk or a GP100?

Both are very good usually and both can be improved easily by adjusting the trigger return spring a little but out of the box, I would say the Blackhawk.

I'd suggest a trip to the fun store and try them. I really can't say for brand new guns, but my GP and BH have seen a lot of use and both have reduced power hammer springs and the difference is negligible. I'd say the BH has a tiny bit more creep, but not enough to bother me.

Having done trigger work on hundreds of Ruger revolvers, I'd expect the BH to have a considerably better trigger (obviously only comparing SA to SA). Given a spring kit in both of them, it gets closer together, and I won't say I haven't seen those rare GP100's with great factory triggers, and those rare BH's with really poor factory triggers, but overall, if you had 10 of each and ranked all 20 from best to worst trigger, I'd expect 1-10 to be the BH's.

I've owned 4 Blackhawks and 1 GP100 and the GP had the best trigger by far. Bought it in 2013. The GP is the better gun over all IMO.

This is really an impossible question to answer definitively. Overall, I'd say both models have single-action triggers that are usually acceptable or better, and that differences between individual examples of one model can be greater than any differences between the models.

This type of question is one that can be debated forever & never settled.
Why?
Apples & oranges.
Two different action designs, give them different physics in how they work. As such, combined with each person's individual grip, perceived feel, and how they pull the trigger,,, there is NO way to get a definitive answer.

A bit off topic but the finest rifle factory trigger pull I have experienced came with my red pad Ruger Number 1.