Depends on your price range. I think Rolexes are over priced. They are good. They used to be the best but the competition has more than caught up. Friends Roleves are always losing time and some have plastic crystals. I'd consider an Omega Seamaster or a Breitling Superocean. Both are under $2k. I've worn my Breitling 24/7/365 for 9yrs without a problem. I am rough on equipment. The 4mm saphire crystal still doesn't have a scratch. A friend has the Omega(James Bond). It is a good looking watch. The bracelet seems less durable 5 seg vs. 3. Just my 2 cents.
I would highly recommend "Luminox" watches. I have several of them and I'm extremely satisfied with the product. It is the same watch that is used by the Navy Seals so I don't need to say more about their underwater/diver capabilities. They are reasonably priced and offer a host of designs. Google "Luminox" for more information.
I will 3rd the Ecodrive watch. I have had one since they were first introduced and have made many dives with it. The only problem I have had is I left it in a drawer with no light and the backup battery died and had to be replaced.
Rolex is the Mercedes of watches...and that's not good. As a kayaker, swimmer, and diver, the Rollie crowd I hang with has moved on to newer and better made watches that don't require a 3-5 year "tuneup" in the $400-$600. range. Both Seiko and Citizen make some excellent watches at 80% LESS than a much hyped Rolex.
These are very popular:
My Rolex Submariner sits in my safe. It needs a restoration but it ain't worth the $$'s Rolex charges....I wear a Titanium Eco-Drive 24/7 that is the best time keeper I've ever owned. I don't dive but it's a good swim watch.
Jerry P . . . . Actually the Department of the Navy requested "Luminox" to make watches to the Navy Seals specs. and became the supplier of same to the Navy. They are Swiss made and have an amazing and unique illumination system. There great watches . . especially if you dive or work around alot of water or moisture.
If you want to spend a lot of money, the Breitling is the best. If you want a really good one for $200-$450 buy a Zodiac. I own 4 of them and have worn them for 20 years. Not many people know the watch but it is swiss made and their automatic is a dream to own. I have one on my wrist that I have worn for 18 years now and spent 90.00 on it for cleaning. The jeweler tried to buy it from me. They are very well thought of by jewelers. Ebay has lots of them but try to find one made in the 1990 - 2000 ara. There are many new old stock ones out there. My preference is the Gold Pont auto but the Seawolf is excellent also