Newbie warning: this is one of those contentious issues for which there is no clear answer. Use the search function, and you will find threads capable of flogging an entire ranch of horses to death on this very subject. Amazingly enough, this massive expenditure of bandwith achieves no clear concensus.
Both groups will ride just fine. Neither has any clear performance advantage. Pricewise, theyr'e comparable. Biggest difference is the shifters on the brake handles. BFD. Try 'em both and see which you like - you'll get used to whatever you choose within a week. Campy gear probably lasts longer - I have a 30 year old bike with Campy Record gear on it that is in perfect working order. Obsolete as all get out, but it still works perfectly. Shimano gear wears out about the time the next generation comes along, and you're ready to upgrade anyway.
Of course, if you're a classy sort of rider, impossibly handsome, witty, brilliant, modest to the point of self depreciation, and in general a Renaissance Man, you'll let your appreciation of detailed metalwork and historical perspective guide you to Campy gear. But I'm not biased about the subject. Not the least bit.
