Miaakitanc -
Short answer - the PX4. i've had both, they're both decent, i'd take the PX4. keep in mind, the PX4 comes in several different trigger configurations. as for "the long answer", just read SmurfSlayer's post, he covered it.
trigger pull is a big factor - the PX4's changes after the 1st shot (if you have the DA/SA). some people don't like that and it does mean having to decock the weapon before reholstering, if you don't empty the mag. Glock's trigger pull is the same everytime.... crappy.