I haven't tried all of them, but I like Mobile Defense because it is completely free and it is very accurate. You have several options of finding your phone whether you just want to locate it or if you have really lost it and need to wipe it. It is also great for finding it if you lose it around the house and left it on vibrate because Mobile Defense wakes it up in any state except phone off. Make sure to install this on your significant others' phone(s), so that you can set off the car alarm on them in the most inopportune moment. You will laugh your ass off and they will want to kill you.