In terms of quality control and reliability, Rolex has a small but discernible edge over the Aqua Terra. Otherwise, the Caliber 8900 in the 41.5mm Aqua Terra is world-class, and the watch is a delight to own and wear. My previous-generation Aqua Terra is one of the only watches I own that non-WIS friends and colleagues notice (I guess I wear low-key watches).
I have a couple of watches on Oyster or similar bracelets, and if I were shopping for a new Aqua Terra right now I would probably just buy it on that totally cool rubber strap
If you admire the OEM bracelet then I guess you'll want to buy it that way and then order the rubber strap and deployant clasp from an Omega Boutique, but note that there is another recent thread here discussing the surprisingly high cost of those.
As other respondents here have noted, I would browse the sites of TRF Trusted Sellers and spend ~$4 for a new one or ~$3.5 for very slightly pre-owned. Don't buy an Aqua Terra without the manufacturer's warranty; they've been known to require the occasional repair (usually issues with crown functionality or hour-hand misalignment). Still, it's a dynamite watch to wear, and I recommend buying one.
