Mark - so many of your questions are subjective so you'll find a wide range of opinions. As to quality of construction, it's unlikely any 3rd party would conduct a study. You'd have to hire an expert to try to evaluate each building, but they've all been built with the latest stringent codes and come with new construction warranties, so I'd also suggest relying on your sense of "feel" for quality.
But I'll share some general thoughts I've heard from others, and from my own trips to these buildings. The Infinity seems to get the highest overall marks, and the gym and pool are quite nice, and it's very close to the Emcardero and water - good location (in real estate it's location, location, location). The Brannan has a stellar reputation and a great location... it's been around long enough and stood the test of time... whereas so many other buildings come out with a ton of fan fare, and a year or two later they're 2nd class citizens. Only time will tell if the Infinity can maintain as good as a reputation for as long, but so far many residents, agents and visitors have had almost nothing but very good things to say.
I'm personally not a fan of the location of both One Rincon and The Lansing. Too close to the bridge and related traffic. The 2nd tower at One Rincon is not being built, so the amenities are not what they initially promised. Blu is probably too new to have a real good idea, but lack of sales has led to a really dramatic price drop. So price per SqFt is probably the best there right now, and it's a decent location.
Overall, I'd suggest visiting multiple units in each building, and then sitting tight as the year goes on. Try not to get caught up in the hype. After a year, new buildings like the 2nd released Infinity Tower which only recently went on sale and hasn't started occupancy yet, will be "old" next year with the first re-sales. And re-sales are like buying a pre-owned car vs. a new one. It will be delivered in like-new condition at a steep discount.
That said, prices at The Watermark and Brannan have barely budged... at least for the most desirable units. If you're going for an unobstructed water view condo with outdoor space you will pay a premium. Think "location" both in the property's address, but also in the building itself... eg, it's views
You will find very low prices in units that stare at other buildings, and very high prices in the onobstructed view units, and obviously prices in between when it's a mix.