Tyrant (Resident Evil)
Why you wouldn't want to meet it up a dark alley: It's a genetically engineered super-soldier with major dermatological issues and massive knives for fingers. If it jostles you as you walk past, best not make an issue out of it.
Movie monster we'd like to see it have a fight with...
The Newborn (Alien: Resurrection, 1997)
Who would win? Tyrant, deffo. The Newborn is supposed to be a sinister, blended human-Alien baby type-thing but actually looks like a sort of treacle-toffee skellington. It's just asking for the crushing and the chopping and the Tupperware save-for-later-ing.