"What Difference Does It Make?" and "How Soon Is Now?" by The Smiths.
Both would figure highly in the "awesome riffs" stakes as well.
I'm not a Smiths fan, but totally agree with the above (although I can never remember which of those two is which!)
(I'm a sucker for simple guitar intros - Satisfaction, Money For Nothing, Sanctuary ...
the good ones just grab hold of something in my brain. Probably 1-in-3 AC/DC tracks too ... )