Hard to say, as the two have never faced each other in the comics. That said, Trigon across mainstream universes has conquered more worlds than Darkseid has, so perhaps he has more cosmic “street cred,” ha.

They did fight each other in justice league dark: apokolips war and both darkseid and trigon in that universe are pretty comparable to their prime earth counterparts. So if we are to take that fight into account then darkseid will be the winner but just barely.