A single strap around the water heater was required in California even before the 1989 Loma Prieta earthquake. After that quake however, the requirements were upgraded to dual straps, adding more specifics as to the materials and location of the straps around the tank.
I went with AO Smith over Bradford White, as it is easier to get parts for the AO Smith at more competitive prices.
With Bradford White's tighter control over the supply channel, the basic economics of supply and demand come into play, and where there is less supply, and the same demand, the prices can be higher. Since AO Smith is less restrictive in their distribution policies, more suppliers, including retailers, can carry AO Smith parts, and the increase of options of availability results in more choices of supply. With the same demand, and more choices in supply, more competitive pricing often follows.
AO Smith further provides many of the same products under multiple brand names, such as State, Reliance, American, Kenmore, ProLine, Whirlpool, Lowe's, etc... which further broadens the availability of parts through multiple supply houses and retail channels, for professionals and DIY'ers.
When I purchased my most recent water heater, under the AO Smith brand, I found it's identical twin in the State, American, and Reliance brands, and downloaded the parts diagrams, part numbers, and sell sheets of each of those brands as reference... not only for part by part comparison and verification of identical-ness, but also for future service, should any be necessary.
Bradford White presented fewer outlets and options in that regard, without any evidence of producing a superior actual product. I've inspected several Defenders, and did not find them to be superior in design, materials, or function over the higher line AO Smith models I also compared.
Obviously, professional plumbers prefer to promote a brand that supports the profit margins in the plumbing trade, and that offers a product exclusively available to licensed plumbers, so as to prevent the very competition discussed earlier in this post. It makes perfect sense for plumbing professionals to talk up and promote a product that can only be obtained by professionals, and cast aspersions on AO Smith, which no longer "protects" the profit margins of the trade, by allowing their brand to be sold in Lowe's.
But setting aside business and brands, and looking at the actual water heaters and warranties, I found a water heater that offered a 12 year warranty, with widely available parts, competitively priced, offered under several brand names, with broad and varied channels of distribution.
Since the opinions of those with the greatest amount of experience can still be tainted with a profit motive or professional agenda, some independent thinking and actual product examination are additional menu items in the feast of information to arrive at an informed decision.