Whichever one you like more.
I went with a HK USP Compact in 9 for my first. Last Monday I picked up a P226 also in 9mm. I haven't handled an XD.
I love both the HK and the P226 but I don't have a good holster for the 226 so it has not seen much time on my hip.
My HK has a nice trigger; the p226 is even better. The SA pull on the 226 is lighter and very crisp. The DA pull is heavier but smooth.
My first impression is that the 226 is too heavy for me to be an everyday carry gun but maybe if I get a proper holster my mind will change. It's great fun at the range tho. I got my most precise grouping ever with my P226.