Hello: As to brand, I care most about service after the sale. If warranty repair or replacement is a hassle, it’s even more of one if you get to go without hot water while dealing with it. So, look into warranty/return service at the stores and see what they tell you. Reading reviews on the web is good too.
About insulation: the best way I know is to bring a tape measure to the store and actually measure insulation thickness. With electric heaters, this may mean removing a hatch cover to be able to measure distance between the outer cover and the tank. Two inches is better than one and three is rare but wonderful 😎