Having gone through the same decision, I prefer the LEM hands down for a defensive trigger.
To me the LEM compares favorably with a striker trigger, but with a longish take-up (like a 2-stage), and a clean break. It's also "auto de-cocking" (no reason to de-cock, let the trigger forward and it's there), and gives you the warm/fuzzy of being able to thumb over hammer while holstering. It is not for everyone, and some guys flat out don't like it. I find it easier to shoot than either a DA/SA or DAO (which it is, but only different)
What model pistol are you looking at??
Depending on the pistol, you can always buy a DA/SA, then convert it to a LEM later, this is the route I've taken with a couple of my HKs. Parts to convert usually run under $100, that way should you dislike the LEM, you can always swap it back to DA/SA.
Here's a pretty good write up:
pistol-training.com » Blog Archive » Why I Like the LEM
and
pistol-training.com » HK LEM vs. SIG DAK
Chuck