My vote is for the LCP. as stated already its just a high quality gun. Fit & finish is nicer, it functions great and I liked the grooves in the sides where your trigger finger and your thumb rest, it just feels better in my hand.
I acquired the Kel-Tec P3A shortly after it came out because, at the time, it was receiving positive gun writer write ups, was a small size gun with a caliber (.380) that I consider a minimum for a defensive handgun and being small was very easy to carry. I mostly pocket carried it until the Ruger LCP became available. After handling and shooting the LCP, I acquired it. The LCP, to me, is of better build quality and has proved to be a perfectly reliable weapon. While I am not a DAO fan, the .380 market at the time was devoid of other reasonable options in this size range. I subsequently sold the P3A and have not regretted the decision. Obviously my choice between the 2 guns is the Ruger because of its perceived build quality and its complete dependability. I have to admit that I am Ruger bias as I own several Rugers all of which I feel are utilitarian but quality made weapons. The guns simply do their job as advertised. Timely, I just read a post here that Ruger has very recently updated the LCP with better sights and a shorter trigger pull and the gun should be or is available now.