I've never handled the Elzetta, so I can't speak from experience on that one. But from what I've heard, they should be of comparable quality, reliability, durability, etc. The prime differences would be:
Size - The LX2 is slimmer, but it's also longer than the Elzetta. If you're looking for pocket carry, the LX2 will probably be more convenient in this regard. But if you're looking for a firm, hand-filling grip, you might prefer the Elzetta.
Beam pattern - From my experience, the M60 module has a much smaller hotspot than the LX2, and less throw (certainly not a slouch there, just less than the LX2). On the other hand, the Elzetta's M60 will give you much brighter and wider spill than the LX2. If you're looking for as much throw as possible, the LX2 would make a better choice, but if you want a more balanced beam (between flood and throw) I'd go with the Elzetta.
UI - The LX2 operates just like any other momentary/twisty, but with the added benefit of being able to only push or twist part way to get a low level. Very simple and intuitive, and great for anyone who doesn't mind a momentary/twisty. Plus, when you're twisted to constant-on on low, you can still momentary press for high. From what I understand of the Elzetta's 2-stage switch, it's basically a clicky that allows you to set brightness by twisting to a certain position. If you prefer clicky switches, this would probably be the better choice, but you wouldn't get the momentary access to high when on constant-low like with the LX2.
Personally, I'd rather have the LX2, as its slim profile and clip allow for great pocket carry, and I'm a huge fan of its optic (plus, its easy to throw an F04 diffuser on there; not sure if a diffuser exists for the Elzetta). Also, somehow I trust the LX2's window to be more durable/resistant to impact than the M60's optic (though I haven't tested this). But I wouldn't say either of these is inherently "better" than the other.