Some people are Groupset groupies, and swear by what they have. Some things I picked up on (with my limited knowledge): Campagnola, have not really changed the basic operation of the shift levers since STI's were invented... still a thumb shift (which seems backwards), which is too much like entry level Shimano Sora. How is it possible to shift in the drops? What happens it you fall? Do the levers just break off cos they dont fold in? Campag also has a cult following and its members are known to tattoo campag on themselves - so it must be good (one must remember, the VW beetle also has a cult following, and it is by no mean the best car...) Shimano, hated by almost everyone. But arguably the most common. With the most victories, the operation just makes sense. one lever for up, another for down. Brakes are the best in the business. It's mass produced, and is much cheaper - and that is it's downfall, no exclusivity. "My fat neighbour even has Dura-ace" The saying, "Tall trees catch the most wind" comes to mind... SRAM, New kid on the Block, the name of a band, was a huge hit in the 90's then faded out... Apparently, Rival and Force where prototypes to RED. So if you gonna get it, get RED. Huge success in MTB'ing, but the road stuff is yet to prove itself with regular people like you and me. If you read any review of SRAM, they talk about the irritation of the derailleurs constantly needing adjustment, and unless you on a pro-team with a mechanic, this could be annoying... Red is possibly the most exclusive currently, and I think even the most expensive, and you will be the envy of everyone, but when you keep asking your mate to borrow his star-screwdriver to adjust your front derailleur halfway through your weekend ride... Double tap, really makes sense- nice to see one manufacturer moving forward.
