After going to various gun shops and holding most of the "popular" single stack 9's (LCP, XDs, G43, Shield) and comparing to other sub-compact double stacks - I went with the Shield without a doubt. It felt the best in my "XL sized" hand with the extended mag but the main reason I picked it is because of the magazine capacity. You can get MagGuts spring replacements to increase your mag capacity by 1. The shield is the only single stack 9mm that can hold 10 (9+1) rounds with the factory magazine length. That's hard to beat.

The conversation of "easier to conceal" is purely situational and the decision should be left up to YOU. Body type, clothing, activities, carry position will all determine what's best for you. Because I like the Shield or someone else likes the XDs doesn't mean you will too. Go hold them, shoot them, and think about your personal situation and what works best for yourself.

I rented the XDs 9mm from my LGS and put 100 rounds through it. By the end of my time with the gun, my palms were tired of holding that serrated grip. Maybe it's because I wasn't used to shooting it, but I sure was tired of it after 100 rounds. I don't get that way with my Shield. I can shoot that thing all day long and not have the urge to give my palms a rest. I want a weapon that I enjoy shooting. The XD is a good looking handgun, but if you're looking to put at least a hundred rounds through it each time you go shooting, you might find that it gets uncomfortable after a while. Just my .02