I have accquired these four guns over the las t several years for the purpose of concealed carry. I have shot all of them quite a bit, but today was the first time I took them all to my farm range for a back to back comparison. All of my shooting was from pocket carry at 4 yards, alternating between point and shoot and then using sites, double taps, silohuette targets Here are my observations:
642 - Pretty concealable, partially due to the hammerless revolver shape. Boringly reliable. Able to put all shots on target with point and shoot. Able to put a couple in the 10 ring with sites. Recoil is significant but acceptable for close encounter self defense use and short practice sessions.
LCP Custom- Most concealable of the group, probably its' biggest asset. Point and shoot accuracy was not all that great. All shots were on the target but usually low due to the way the small grip fit my hand. With sites I could put the majority of the shots in the 10 ring. Recoil was significant due to size and weight, but not as much as the 642. Cycled reliably.
LC9S - Maybe a little large for pocket carry, but it is a 9mm. Had to remember the safety. Point and shoot accuracy was pretty good with most shots in the chest area. Accuracy with sights was excellent due to the very nice trigger. Recoil was snappy and the trigger would always pinch my finger. Cycled reliably.
Glock 42 - Not as concealable as the LCP but not bad in the pocket. Point and shoot accuracy was very good, best of the group. Accuracy with sights was outstanding, again best of the group. Recoil was very pleasant and again the best of the group.
It also cycled all ammo reliably.
After I finished with the comparison, I shot the Glock 42 another 50 rounds just because it was so accurate and so enjoyable to shoot. IMO it was the only one of the group that could double for defense and as a range gun. Its superior accuracy makes it a good farm gun to dispatch small varmints.
All are good guns, but I think the Glock 42 gets the nod over the other semis. However, I still won't leave home without my j frame, its just too functionally simple and reliable for self defense. Maybe not for farm carry though.