Taking burn to empower the shield is like trading out Thoughtness for Dodge. Witch talent do you think is more usefull?
The force ward hit points come back. and with the boosts to con, you end up with equal or better net hp than a standard character of that con. at least until you decide not to bump con or max out the boost. Which is much better than any other kineticist.
I will agree that campaign variation affects how useful each talent is. A low wealth game favors water. A game with common guns makes earth and air stronger.
but I stand by my rankings for average games.
I am glad that different people like the different defenses. It makes me happy when guides can't quite decide which is the best because, as an optimizer myself but one who likes having lots of options and optimizing starting from a character concept, it makes me feel like there's a lot more possibilities out there than when there's one true build that everyone agrees is the best way to go with a class.
I've seen some good results from both water and aether defenses. One fun thing you can do with aether, if you want to be the queen of hit points, is blow your entire internal buffer and also an overflow amount of burn into temp hp. At 6th, for instance, you've taken perhaps 18 nonlethal from burn but you can generate +2 Con from overflow for 6 extra hp and 15 temp hp from force ward, so counting the ward, you are 3 hp farther away from unconsciousness than a non-kineticist with the same Con and 21 hp farther away from death.