I don't currently pocket carry so please take this with a grain of salt.
The Ruger LCP is a very popular choice. I have a small amount of trigger time on the one my mother-in-law owns, and I didn't like it. Snappy because it's so light, hard to cycle the slide (maybe hers just wasn't broken in very well), and just generally not a pleasant shooter. However its size lends itself very well to pocket carry. I have been tempted despite not having a pleasant shooting experience.
Another popular choice is the Kahr. I shot one of their subcompact 9mm's and it hurt the webbing of my hand between the thumb and forefinger, after less than 50 rounds. However, I personally greatly prefer the Kahr over the LCP. The trigger was nicer and the slide was easier to manipulate.
There are many options that fill this niche nowadays. Ruger LCP, LC380, LC9, S&W Bodyguard, Taurus makes some, the Kahrs, Sig P238, P938, Colt Mustang, even Glock has the model 42 now.
I suggest going to a couple gun stores and holding as many as you can. When you find a couple that feel "right" in your hand, see if you can rent them to shoot.
My choice would probably be the Sig P938, because I prefer 9mm over .380 and really like the feel of that gun. A little expensive though. Or maybe a Kahr in 9mm, because the Sig has a thumb safety that I'm not keen on.
Oh another one is the S&W M&P Shield in 9mm. I wish that gun didn't have a thumb safety. I might already own one despite the fact that its a little bigger.