these both rank high on my list of fave voyager episodes.
if pressed, i'd choose 'scorpion'. the shine has worn off it just a bit in subsequent viewings, but when i saw it for the first time i remember being really impressed. of course, that was back when the borg were still scary...
also, i think the general quality of voyager improved from 'scorpion' on with the addition of seven of nine. (i am NOT a guy, so not for the reason you might be thinking!
i simply think the character allowed for the development of more interesting episodes.)