Two shot is by far the best for single shot weapons, with the exception of shotguns. for automatic weapons it's a bit trickier, if the affix is adding more damage than the shot itself, it's better with burn&bleed etc, if not, 2 shot as well. Shotguns effects (like bleed, explosive etc) is per pellet, not per shot. It is unclear to me how many pellets you have, but from testing with a 2 shot combat shotgun with max mods compared to a 25 bleed combat shotgun with same mods, the bleed is way better. It might even be that the 2 shot only adds one more pellet, as it is not 2x the damage of the basic version.
Instigating is not too bad either on very high damage weapons like hunting rifle and gauss gun if you want to use them for sniping.
It is hard to evaluate utility stats like the criple, but those are very good if you feel that you don't need more damage ofc. To each their own. On lower difficulties they might even be preferred. personally I have been sticking with damage though, since I modded so that I do almost 2x the damage of survival, but enemies does 2.5x vanilla survival, so damage trumps any alternative stats from my testing.
Edit: after some testing it appears that poison doesn't stack for multiple hits, so that is not very good, on shotguns in particular since you only get one instance of it despite the many pellets. Might be same with fire, but explosive and bleed should stack for sure.