I hate mind control too, and confess to occasionally using save/reload when I get pissed at results. I mean, if aliens have mind control capabilities, why do they bother with weapons at all? They should just sit behind a fortified door and mind control us one by one, and have us kill each other off and/or commit suicide. Nevertheless, the tactic I prefer to deal with it, is to disarm each soldier at the end of each turn. Mind-controlled troops are too stupid to look in their backpack for a weapon. Thus, you can arm the trooper, fire an aimed shot, return the weapon to backpack, and move on to the next soldier. Of course, this means forgoing reaction fire each turn, so I will sometimes play Russian roulette, and keep some of the soldiers armed.
(Note, in the original X-com, the X-Com Utility made it possible to disable mind-control altogether. IMO this made for a much better game!)