Best handgun trigger? A 1911.
Close runner-up to the BHP.
Seriously, though? Trigger feel is, after a certain point, all subjective. I'd never try to insist that one gun or another has a better trigger. I will, however, tell you what ones I like and dislike. The problem is that each person will do that and give you different answers. After you reach a certain level of quality, there is no right or wrong, it's all about which works best for you.
That said, I'll give my utterly unscientific and complete subjective rundown of duty gun triggers with which I have fiddled around.
M&P: Love it,
after it is cleaned up by some dryfiring. I was reminded of how gritty and busy the trigger feels at first when I fist played with my new M&P40C. S&W might well be saving money in the finishing department by not working the burrs and hitches off of the trigger mechanism, but I cannot help but wonder just how many purchases they lost when people went in, picked up a brand-new display gun, pulled the trigger and went "Ehh." It's a good trigger, once you work it a little. Also, it is amenable to easy improvement by a gunsmith.
Sig DAK: Not bad. I don't recall being really impressed, but I also was not put off by it. It was pretty clean (not very busy or gritty).
HK LEM: I think I played with one once. It was OK.
Glock: I have a Glock 20, which was set up with the standard trigger, which has since been replaced by a 3# trigger. The whole thing is spongy, creepy and vague. Even the break seems oddly drawn out. Can you get used to it? Sure. I got used to driving my wife's 95 Nissan Sentra, too. Doesn't mean I liked it.
Seriously, I can't really find anything good to say about the Glock trigger, except that it is not overly heavy. Note that many people do use Glock triggers to great effect, and there are many who can outshoot me with it. I just don't like 'em.
S&W Gen 3 DA/SA and/or DAO: Most of my experience is with the 4506, but they all seem pretty similar. The DA pull is long, stiff, with some stacking and grit. The break is crisp. The SA is really short and pretty stiff (for a SA). Lots of overtravel. The DAO models seem exactly the same, with no SA and a somewhat shorter pull.
S&W99: Blah. Nothing bad, but nothing really memorable.
XD: Pretty good. Had a bit of plasticy feel like a glock, but it was more clean and defined. Broke smoothly. It seemed conducive to pretty good accuracy.
Of course, these are as-issued. I have no idea what a smith could do to some of the triggers.
Mike