Sometimes it's fun to pit two classics against each other and try to figure out which one comes out on top. For this comparison, I'll look at the Rolex Sea-Dweller and the Omega Seamaster; two incredibly popular and robust watches that do exceptionally well as both 'desk divers' and while battling a few atmospheres of pressure in the underwater world.
Before we get started, I should say that I've done a lot of scuba diving and truthfully neither of these watches would be my first choice for diving (currently I dive with a Seiko 'Monster'... more about that some other time) but both are absolutely competent and capable in that realm.
The case of both of these watches is substantial and rugged. The Rolex is 14mm thick and 39mm at the bezel. It feel much more substantial than it's 'little brother', the Submariner on your wrist, weighs more, and takes a lot more abuse too. The Omega is 11mm thick and 37mm across the bezel - slightly smaller than the Sea-Dweller so it slips underneath a shirt cuff a little more easily and doesn't have the nasty habit of getting 'stuck' in doors that the Rolex does.
Both the Rolex and the Omega use crowns that are substantial, easy-to-grip, and that incorporate very good waterproofing measures. The proprietary Rolex system is called the ' Triplock ' and has become somewhat of a legend in the watch world. The Omega system is equally well designed and both make it easy to screw down the crown after setting/winding and provide a water-tight seal.
Both the Sea-dweller and Seamaster have uni-directional positive click bezels that are easy to read underwater. This is extremely important if you are actually diving with your watch since a bezel that turns in both directions could easily brush against something and suddenly indicate that your bottom time was much less than actual - a real problem when you are trying to avoid decompression stops and don't have a penchant for the 'bends'. I find that the bezel of the Omega is the easier of the two to turn with wetsuit gloves.
The bracelet on the Rolex is the infamous Rolex Oyster Bracelet. It can take a silly amount of abuse and can be easily adjusted. I don't think it's the most comfortable watch bracelet ever created. The edges of the links are a little on the 'sharp' side especially when you cock your wrist to open a door or swing a golf club (not recommended of course... but it happens!). The Omega bracelet is more comfortable to me. The locking mechanism on the Sea-Dweller clasp is a flip over mechanism while the Seamaster uses locking 'buttons' on the sides of the clasp to provide extra security. Both are very effective. I think the Omega clasp might be a little easier to deal with since it's sometimes tough to get a fingernail under the Rolex's safety latch... but this is definitely nitpicking.
When it comes to price, the Rolex is definitely more expensive. It's also much more likely that you'll get a nice discount on the Seamaster than it is that you'll save anything on the Sea-Dweller's MSRP. If you decide you need a change of pace and sell the -dweller, you'll most likely get very close to what you paid for it (maybe even more!). You'd have to buy the Omega very 'right' to avoid a substantial loss when selling it.
It's impossible to escape the status that wearing a Rolex... any Rolex... conveys. Even people who don't know a thing about watches, recognize a Rolex watch as a trapping of a successful life. Unfortunately with replica watches outselling their legitimate cousins by a factor of almost 10, the cache of wearing a Rolex might be suspect in some circles. Among those knowledgeable about watches, I think it's safe to say that both of these watches enjoy a pretty equal footing and a very respectable reputation.
If there's a budget to consider, buy the Seamaster and don't look back... it's a great watch that you'll enjoy wearing. If you're still riding high from some masterful IPO, opt for the Seadweller... it's a watch that you should have in your collection and one that you'll find yourself wearing a lot.
Still can't decide? Buy both! Life is short.