Investigators should check lurkers and players who tend to be mislynch bait. In short, essentially prioritize people who are hard to read in general. Checking a wolf read is bad practice as if they end up returning a red check then you’ve technically wasted a night as you could’ve easily nabbed them on reads alone, while a green check on them would have been better put to practice on another player. Checking a village read is unbridled paranoia here and will almost in all occasions net an obvious green check.
Additionally, in a match with framers, lawyers, and tailors in general a suspicious village player will be the priority target for a framing while a suspicious wolf player will likely be tailored, so something else to put in mind.