An indirect should really last 30 with good water conditions, Everything will leak sooner or later and I try not to form an opinion on the first two or three.
There are only a few players. I like Triangle Tube, Buderus, Viessmann, Mega-Stor. I am trying to track down all of the OEM's myself, though I think you may get better service from the Brand Name companies that buy and sell rather than make their own.
It all comes down to service.