The Ruger LC9 has a long trigger pull, has already been mentioned, and I'm not a fan (I had one.) Ruger makes a compact gun, the SR9c, which is a good pistol and it very inexpensive compared to others in this category.
Kahr guns, IMO, have very good triggers...they may be long, but they feel very smooth and light. You can get a CW9 for a very reasonable price, but the mags are (IMO) expensive...but then, what mags aren't these days?
S&W M&P9c is a very good choice, and is a very good carry gun. You have the advantage of higher capacity, interchangeable back straps, and you can use the full size M&P 9 magazines in the compact, for shooting at the range, etc.
I can't comment on the Beretta Nano, since I've never owned one...but I have had other Berettas, and their CS is poor. The 92FS/M9 is very reliable, however, but it's not in the category you are looking for.
Taurus makes some small carry guns, like the PT709 Slim, but I wouldn't recommend any Taurus products (after having owned a few.)
You could consider a Glock 26, but it is a fairly chunky handgun, compared to the M&P9c or especially the Shield.
Bersa has out a slim 9mm, the BP9CC, which is comparable to the Shield, and reasonably priced. I owned one very briefly, and then traded it...mine had a trigger that was scary light. I mean, it couldn't have been 2 pounds! That's just too light for a gun with no safety. They are noted for having a light trigger, and maybe mine was just an unusual case, since at the time the LGS didn't have any others to compare it with. I would definitely dry fire it in the store, if you consider that model!