Fate/Grand Order III - Protecc those Smiles

[spectralphoenix]

So then what's the best proportion of these CE's to mix? Do I want to MLB the ones from the shop right away and fill up the rest with the ones that increase drop chance (if I luck into them, anyway?) Am I better off going 3 that boost drop chance and 3 that make extra enemies? Something in between?

The best case is to MLB the shop CEs - the spawn bonus maxes out at 100%, so you can get the whole bonus with one CE slot. Past that, use as many drop bonuses as you can. If you don't have it MLB yet, drop bonuses are probably a better value for the slot until you have a bonus of +3 or greater. Make sure you're using the right CEs for the mission! Bringing a +copper CE to a mission that only drops silver is a waste.