Se-LSI is definitely up there. The combination of being quiet, yet forceful and willing to judge, as well as quite blunt, can make them pretty scary. LIEs are also up there: some of them just make me feel dumb because they seem to know SO MUCH about EVERYTHING They can be pretty rough to argue with: they're really good at directing the debate wherever it is they'd like it to go, and I definitely have to put in an effort to make sure my conclusions are heard and made explicit before they try to switch gears on me.