I would save my spell till a life-threatening situation, then use Wingardium Leviosa to move an enemy or get a weapon.

It's a hard one. I guess you're right though - WL is more likely to be useful in a life-threatening situation whereas Lumos is just light.

I didn't realise from the question that it was a one use spell. I just chose one at random.

Wingardim Leviosa is much more useful, though I suppose my opponent could still block it somehow.

Well, I'm afraid of the dark..this would come in handy.

I guess with Lumos you could also blind someone and then use the time to run away.

I always use this spell when I need some light...even if doesn't work , lol

^^^ Yes.

@linhousepotter - I try the same

@linhousepotter and @ Flickerflame me too with Accio :P