Originally Posted by oboe
Please compare Campy, SRAM, and Shimano - I'm only familiar with Shimano and want to learn the differences.
What will you be doing with the components? Racing, recreational riding? How many miles/year? Campy can shift either way several gears at a time (2006 and older at least) and Record is lighter than Dura Ace (most of the weight savings is on shifters and crankset). Record is very expensive. I haven't tried the new SRAM Red, so I can't help you there, but it promises to be good. I have ridden Rival, but both my road bikes are Campy equipped, and my TT bike is Shimano, so I have more experience with these two.
I prefer Campy (even Centaur is great) due to the fact that the indexing is heavier, the components seem more durable (rebuildable, and use harder steel/titanium, whereas Shimano relies on lots of plastic). I get about 5,000 miles out of my rear shifter before I send it back for a rebuild, and it comes back good as new (I probably ride 8,000 miles a year, so this is fairly handy). I have crashed many times on my Record rear mech and it still functions well. My Chorus cogs have been on my bike for 2 seasons and seen a ton of miles, and still are great (Dura Ace cogs are softer and wear quickly). Campy chains wear longer (harder steel perhaps)? Braking-wise, they are comparable, same with cranks (although some have had trouble with the UT bearings). And, the Campy Ergo shifter fits my hand better than STI. Overall, for the extra expense of Campy, I prefer it, as it seems to do it's job very well, last infinitely long (and can be rebuilt), and has clean lines and a classic look to it. If you are on a limited budget, the Centaur group is every bit as good performance wise (except for the shifters, look for the 2006 product) as Record, but an extra 250g and 1/2 the price. It blows Ultegra out of the water, IMO. Campy also has the most durable alloy wheels around. I run the Neutron and that is a bombproof wheel if there ever was one. These are the best hubs in the business. The high-end Shimano wheels WH-7801 SL are very nice, but stay away from the lower end Shimano pre-built stuff. Campag Zonda is much nicer. If you have an Italian bike, you could (should?) be thrown in jail for running Shimano on it.
For mountain components, I run XTR. The XT stuff shifts well, but the shifters have a very non-positive, plastic feel. The XTR shifters are great, as are the derailleurs. I run XT for cassettes, as XTR is ti and wears quickly. SRAM X9 is every bit as good though, as is XO, but a little pricier. I would recommend the one that you can get the best price on. Look elsewhere for brakes, as Formula, Hope, and Magura all have superior brakes to Avid and Shimano.