well, playing with any of my quarians makes me feel dirty and in need of self sterilization, but for these two in particular I have to load up on the immuno-boosters.
QMI
There's not really a way to play him that isn't, but for going full cheese on this smexy man beast, I used to just run Claymoar, lolcarrier, BW, Arc Pistol or whatever and they all work extremely well to the end of making all the things extremely dead. CSR with cloak bonus does almost the same damage per shot as the Carrier on him......but it fires 300 RPM faster and stacks teh cheeze better than almost anything that isn't the Reegar (which is also dirty on him, but I want to include some variety). If you can use the scope in CQB, it is one of the best assault rifles there is. It also keeps tacscan's cooldown low. He dominates, talks dirty and you never see him cumming coming, and I like that. Keelah se'lai, bosh'tets.
QME
Whoever said there's no time for aerial bombardment when this dashing, lore friendly gentleman is around? Pretty typical no fitness with arc pistol build. Enables you to pump out a 6/6 fire explosion or Tech burst, all game, every 3 seconds or so, charging and firing your quarian pistol all the time. He just explodes and keeps exploding. Mooks never have a chance to react before being burned, blown up and then electrocuted by what he discharges. Bosses might realize you are there, but tacscan's 32.5% multiplicative weapon damage buff, combined with 100% damage double hits on the Arc Pistol means they don't stay standing for very long. Nuke it from orbit, kill it with fire. Kill it all with fire.
I can't play either of these for very long before I'm running a fever, get a nasty cough, and have my sinuses filled with something that is indescribable. Nonetheless, it is always totally worth it.