uscpsycho: Most of the parts on a water heater (controls, etc) are made by couple of manufacturers. Within the standard gas or electric tank water heaters much is going to be the same. Bradford White I believe is still only sold to licensed plumbers (they aren't available at Big-Box hardware, for example). Plumbers like to install them because the end customer can't see the retail cost of the unit (and the markup for the plumber). The brand has some "reputation" for quality because that's what the homeowner is told as a justification for the higher price. In addition, a professionally installed heater will generally have fewer issues overall. The point being that the hardware may not be better, but because Bradford White isn't installed by do-it-yourselfers, it can claim a reputation for better reliability. I'm reading the same issues about warranty that you are. In general my feeling about standard tank water heaters is that they are pretty much a commodity item. I've had good luck with Rheem - and a 40 gal, 12 year warranty is $560. Avoid too many bells and whistles that don't really add value (do you really need your water heater to like you on Facebook?) There are other types of water heaters - as you learned in your other post that went wildly off track (sorry about that). But I think that JRB451 is closer to right than wrong. If you start getting into condensing, or hybrid electric, or even fiberglass tanks - then things are different.

We have a Rennai, gas tankless. Very happy with it. It was more expensive than a conventional water heater, but the endless hot water is well worth the expense. When we have guests, generally we add eight people to the house for a week at a time, an impossible situation for a conventional water heater if everyone wants a hot shower. It has been completely reliable and trouble-free.

That depends entirely upon the number/types of fixtures you want to be able to run at the same time without dropping temperature and the inlet temperature of your water. A tankless water heater's heat exchanger is specified for a certain temperature rise at a certain flow rate. If your inlet water is colder, you will need a larger heat exchanger. The $800 your GC has quoted you has to cover the additional cost of the tankless plus the additional cost of a larger fuel line to the water heater. Generally, builders will pick a smaller, cheaper unit that saves them money but does not necessarily meet the needs or desires of the homeowner. In case it matters to you, I only have personal experience with two brands - Rinnai and Noritz. With essentially the same specs, the Noritz is of much better quality, all the way from the heat exchanger (Rinnai's failed catistrophically twice in seven years) right down to the paint they use on the box. I can't speak to Nortiz's customer service (hopefully that will continue to be the case), but Rinnai's is terrible. You will want to ask about the water heater brands, tankless and traditional, your GC is proposing and do your research before making a decision. My decision to go with tankless was driven by a child with breathing problems that are greatly helped by very long, steamy showers, frequent guests, and utility room space. Your situation is likely entirely different. If your decision is primarily financial go with a traditional water heater. If you have other considerations, you may wish to consider tankless.

which water heaters are great for attics with least amount of water leaks or corrosion or dangerous explosions.