Components

Try to find two (or three with Campag) with the different groups spec'd and see which hoods feel the best in your hands. Find what level fits into your price range and go with that. On you next bike you can make the call if you want to stick with that group or if there is some aspect of it you think is better handled by another group. SRAM and Shimano have interchangable wheels/ cassettes while Campag is slightly different. In the end, the component group is going to hold a tune/ shift smoothly if set up correctly and not cost you because you don't have the highest end or this brand. Rival, Ultegra, Centaur have all proven themselves to be very durable -- I would start with those and then see where it goes based on the price range you are looking for. Ultimatly, the feel of the different hoods is in my opinion the best place to start with you initial choice.

The law of diminishing returns is very prevalent in bikes. With Dura-Ace, SRAM Red, Record or Chorus, you're getting very nicely finished and very slightly lighter components for a lot more money. Most people agree that "bang for the buck" is with Shimano 105 or Campy Centaur & SRAM Rival or Force. Some people prefer to spend the extra $$ for the "bling" factor. Just like all other products ... cars, computers .... the mid-level works just as well (or 95% as well), but is not as flashy.

You really should find some bikes to test ride and get your own opinions. Reasonable people can argue all day about why their choice is the right choice and the other choice is the wrong choice.

Frame fit and bike setup are more important than the specific brand or model of components. A bike too big or too small will be a disappointment even if it costs $5000. Stem length, type of bars, saddle, pedals & shoes are important too.

If you search bikeforums.net, you'll find thousands of posts on the topic. But don't ask a vague question like "Which is better, Shimano or Campy" It's been asked and answered over & over, and now most posts like that are considered trolling and you won't get anywhere.

Better to go to the road forum and ask specific questions to get specific answers:

"I'm looking for a road bike in $nnn price range. I live in a (flat; rolling; hilly; mountainous) part of the country. I'm n-feet tall, weigh x lbs, am x years old. The type of riding I want to do is (racing; touring; pleasure; fast fitness..). I hope to ride x hours per week. My current fitness level is XXXX. My current activities are XXX, for the last xxx years .....

Most people (including me) will suggest you go to your local shop & test ride some bikes. then after you've ridden some, come back with specific questions about the models you've seen and the components they have.

"What's the best bike" Is like "what's the best car" There is no one answer.

Ultegra SL is very nice. You'll think it's awesome until you ride DA(dura ace). IMO Ultegra SL would be perfect for you.

I don't think that DA feels any better than Ultegra and I'm not convinced it lasts any longer either. Unless you want to spend $2 for every gram saved (which is fair enough), then go for Ultegra and put the money saved on better wheels or whatever.

I still prefer Campy but that's a personal thing. A centaur or above groupset should do OK. Record is nice but overpriced, again unless you love to spend money go for centaur/chorus.

I have had no experience with SRAM road gear.

Try before you buy.