An objective comparison, Rolex vs Omega, Eppur si muove (and yet it moves...)

As said previously, I don't find brand comparisons particularly useful. However, they're a popular topic of discussion and can certainly be a useful reference. Rolex and Omega are probably the most compared of any of the brands, possibly because of their relatively close price range and popularity in the general luxury watch market. Instead of declaring "this brand is superior", I'm going to do a step-wise comparison of the brands in general, which one comes out on top will be more a matter of which aspects a user cares more about rather than which is "better". Most of the generalizations I will be making are the more modern popular models, i.e. for Rolex the professional series (Air-king, GMT, Submariner, Daytona, president/day-date) and for Omega their Speedmaster, Seamaster (professional and Aqua Terra), and DeVille. I will not be generally referring to the sky dweller, omega's co-axial tourbillons, the yacht master II or any other extreme examples.

History and company
Omega is, without a doubt, a member of the Swatch Group. There's really nothing wrong with Swatch ownership and this actually allows for them to develop superb movements at a cost efficiency not possible without such scale. Omega had many of its best creations in the 1960's, including the ever popular pie-pan constellation. Despite somewhat declining in the 70's and 80's, the brand had new life breathed into it when it adopted George Daniels' co-axial escapement in 1999. This, and subsequent events in the early 21st century gave Omega a more modern brand image, despite the company's older age (1848) than Rolex (1905). Omega is noted for three things historically: The NASA Moon landing, chronometer/observatory trials, and their co-axial escapement. Unlike Rolex, they release many special and limited editions which while interesting, I personally find gaudy and an over exploitation of their history, especially considering that the current "moon watch" Speedmaster has a very different movement than the original column wheel Lemania in the cal 321.

Still an independent company, Rolex is much younger than Omega, but its historical technical achievements are arguably greater. Rolex was the first to introduce a truly waterproof watch, it was also the first in GMT, divers, and automatically date changing watches. These unexciting but extremely practical accomplishments have been a theme for the brand throughout its history. Additionally, Rolex has held a stronger popular image than Omega, being worn by James Bond (in the books and early movies), Fidel Castro, and just about everyone else. Its exceeding popularity is also an issue, with production fluctuating around the 1,000,000 watches a year mark, Rolex is actually even less exclusive than Omega. Despite its prevalence, its history with Comex and Pan Am certainly put Rolex in the history books.

Movements
Quartz movements aside, both companies use well made, but not exceedingly well finished, movements. Omega has continued to forge ahead with its 8500 series co-axial movements while Rolex has taken a conservative approach and continued to use their 3000 series movements (with the exception of the Daytona). The key differences between the movements are: Rolex uses a breguet overcoil hairspring made of their parachrom blue antimagnetic alloy while Omega uses a flat hairspring made of a silicon alloy. Both use free sprung balances with variable inertia balance wheels and this is more or less a tie. Rolex uses the conventional lever escapement while Omega uses Daniels' co-axial escapement. There is plenty of information about the differences between the two but the theory is the co-axial does not involve sliding (rubbing) friction and this is more durable, but on the opposite hand it beats at 3.5 hz instead of 4 hz, while the technology is intriguing their is little to suggest it actually will last longer since a properly maintained lever escapement lasts an extremely long time anyway. But as in all things horology, theoretical advantage is often enough. The winding system of Omega is more durable but slightly louder than Rolex, Omega uses the conventional ball bearing system while Rolex uses a jeweled post. The issue with the jeweled post is that if the lubrication runs dry, the post will wear down and the weight of the automatic rotor is likely to scrape against the mainplate, wearing down the rhodium plating. The exception to this is the Daytona, which uses ceramic ball bearings.

Omega 8500 caliber showing the free sprung balance, double barrels, and co-axial escapement

Rolex 3136, notice the lack of ball bearing, blue Breguet overcoil hairspring, and free sprung balance

904L vs 316L Steel
Rolex continuously markets its use of 904L instead of 316L steel, Both grades of steel are high quality, but the Rolex reasoning is that because of professional diving use, sea water was found to slowly seep into the threads of the caseback. This causes corrosion in 316L and thus the change was made. This change is interesting and a nice touch, but again, not particularly technically meaningful to 99.9% of users.

Case, bracelet, and clasp
The cases made by both companies are comparable in quality, Rolex tends to be shinier and more "bling" with polished surfaces while Omega's use of brushed metal is more subdued. The ceramic bezel introduced by Rolex (and adopted by Omega) is a nice touch, making the watches look more modern. While it's nice to have a unscratched bezel, the lack of potential patina could be a downside (as is the high cost of replacing the bezel). While Rolex had a pretty abysmal hollow stamped link bracelet previously, its new solid bracelet is significantly better and feels slightly better than that made by Omega. The new Glidelock clasp is well machined, but there have been reports that the clasp is not as secure as it could be.

Rolex Glidelock clasp

This was previously covered in my review of the 14060M Submariner

Price, aesthetics, and others.
When it comes down to plopping down paper or plastic for whatever purchase, it's ultimately a personal decision. It's important to consider mechanical, technical, and historical factors but if you end up with a watch which you don't like, or can't afford, it really does no good. As always, buy what you can afford, buy what you like.

An interesting boxplot graph of 2011 watch prices by brand, Rolex and Omega both lie in the same tier