Bunker spec is nice and all, but it doesn't mean much in the greater scheme of things. Having one spec, with one weapon, which excells at a very specific role in only one aspect of the game, is a far cry from a fun and balanced class.
This. If you judge a class on a situational build you're doing something wrong. There is no way to get a clean across the board comparison going. 'My bunker is unkillable unless the enemy..." or "If I go glass cannon I can two/three hit this or that..." are completely worthless comments. They call that cheese builds.
A good build is one that *emphasizes* an aspect of the class without losing the advantages the other aspects of the class have to offer. I can go pure condition but that would still make me weaker than a more balanced setup that also factors in some crit chance and power. I could go full toughness and go wild on defensive traits but that would still kill me because I can not inflict enough damage to destroy things. So yes, Aether and others, you are completely right when you say 'not a single build is really viable'. But you are just approaching this class in the wrong way.
It took me some time to figure out that pure min-maxing in this game simply does not work, at least not for the Ele. I play a Guardian as well and agree it is a far tougher class that can still dish out some frightening damage while taking hits. I've tried all sorts of builds with both classes and got the gear to accompany those builds. I ended up combining several set types to get the right stat balance and stayed clear of the pure glass or pure bunker philosophy. And, consequently, I really don't recognize all these problems people are facing with Elementalists.
Give it a shot sometime.