this thread is like fucking Groundhog day.
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New readers: this thread in summary**
Some people like Campag, some people like Shimano - they like to argue about it. Both are fine, as is SRAM.
Choose your groupset manufacturer based on the comfort of the hoods and shifting action FOR YOU. Do not listen to the internet, everyone's hands like different things.
Choose your tier of groupset based around what you can afford to buy, and what you can afford to replace when stuff wears out. You can always choose to use cheaper chains/cassettes going forward.
Anything over Force, Ultegra or Chorus is probably overkill unless A) you are the next big thing in cycling, or B) are a tart with money to spend.
tl;dr
Buy Shimano.