Velocipedio's road components equivalencies chart [from bottom to top]:
Shimano / Campagnolo
Sora / Xenon
Tiagra / Mirage
105 / Veloce
Ultegra / Centaur
Dura Ace / Chorus
And Record stands on its own level.
Now this is subjective, and a lot of people will disagree with me. Moreover, the equivalencies aren't exact. Tiagra is a little more polished and durable than Mirage, for example, but things even out quite nicely at the top.
The bottom-line serious group from Campagnolo is Veloce, just like 105 is for Shimano. Bear in mind, too, that Centaur, Chorus and Record are all 10-speed groups.