Both for certain. I've had wonderful luck with the LCP. My 442 goes along in the cooler months. I am never without the LCP, but always at least try to carry both depending on attire or situation.
I have long been an LCP fanboy, but I recently took possession of my FIL's 442. I have no plans for moving away from the Ruger as my carry gun but, I have to admit that the little "J" has been whispering to me. My comfort level would be the same with both.
I've got an LCP and 642. The LCP is so easy and convenient to carry. Drop it in my pants pocket in the mooning and it stays there till bedtime.
As far as what I shoot best? Eh... I shoot my 1911s best. But I shoot the LCP to my satisfaction for SD purposes. That I can shoot this or that pistol incrementally better isn't something that weighs heavily on my decision process. The number one factor is that I'm willing to carry it at all times. For the LCP the answer is yes. Other guns in my safe... not so much.
I own both. I also plan to keep both. Recently, I had been drawn to the LCP (it is a fairly recent purchase). Now that the newness has worn off a bit, I find myself back to my old "tried and true" 642/638.
The only real times I now carry my LCP is when even an Airweight is too difficult to conceal. That equals- rarely.
Year round, when I get up until I go to bed, an LCP in a Mika pocket holster goes in my front pocket. It's sort of like carrying a 7 shot derringer.
In the winter, if I'm wearing a coat/parka that makes pocket draw difficult, I put my 642 in my outer coat pocket (also in a Mika holster). If I'm going somewhere I have to leave my coat, instead of the 642, I'll move the LCP from my pants pocket to the coat while I have the coat on, then back to my front pocket when I have to take the coat off.
I hit the range today and did some shooting with my snub, and also my G42. I really like the J, but I'm just nowhere near as accurate with it as I am with my semis. I was easily nailing small groups with the G42, but it took much more effort with the J. On top of that, it's not much fun to shoot (bangs up my hand). The LCP isn't quite as comfortable to shoot as the Glock, but I'd prefer practicing with over the J-frame. I'm sure I could get better with the J, but it'd take a lot of practice. If I'm being honest, I love the gun, but it's probably the one I shoot the worst.
As a side note, the G42 shoots really nice, but my objection to it is, it's about the same size as my LC9s, and it's not very pocketable. If I'm going to belt carry, there's no point in carrying the Glock when I have the LC9.
I always have my 360PD in appendix carry. My back-up and reload is my 3914DAO. Thin and light enough to disappear even under a T shirt. It hides better than my J frame.
ammo is not really a concern with either. use the all lead holloepoints or Speer gold short barrel in the stubby and any round with XTP bullets in THE 380 you'll be fine