Anoints are unfortunately very build specific. I’m not sure there’s any way to make a general rule. Picking the absolute best anoint for a build is going to require knowledge of the damage calculations.
Generally the best anoints are splash, next 2 mags bonus elements, 150% rad or consecutive hits. There are other good anoints but those are the ones that consistently come out on top from the non character specific ones.
I’d try both OPQ’s out and see which feels better. Neither is great, but it should still be passable. 300/90 is a hard anoint to decide on as its very dependent on, if it triggers the shock explosion while 300/90 is active it’ll probabaly win. Otherwise I’d expect the healing pool OPQ tokull quicker.