A few thoughts:
I've owned an XD45 and XD40sc. Solid pistols but I disliked them due to high bore center and vague trigger letoff. I moved onto Glocks.
The XDS is *not* your regular XD, its trigger is all glock, and it wears an external extractor like a Glock. I still had my doubts, but recently had the oppurtunity to shoot one, and honeslty I was impressed by it. The trigger is excellent. I mean EXCELLENT (if you like a two stage and a crisp letoff)! I have a Glock 36, so I have that data point to compare the XDS to in terms of recoil/shootability/feel. The XDS recoil is honestly nicer/easier/smoother than the G36.
If the form factor, cartridge and capacity of the XDS is appropriate for you, the XDS is a winner.
That said, I'm a Kahr PM9 fanboy. I've been through a lot of CPL pistols trying to find my "holy grail". The only pistol that's lasted me more than a year before buying something new has been my Kahr. At this point, I've been carrying it (nearly exclusively) for over 3 years, and nothing on the market provides something better (for my tastes) that I'm inclined to buy with the exception of the Rohrbaugh R9 - but the pricetag is just too much to swallow.
What I love about the Kahr is the combination of trigger (yes I said trigger), form factor, capacity and "firepower". I love the trigger on this pistol. It is the ideal pocket pistol trigger. Even though I carry the pistol in a holster inside my pocket, I still really subscribe to the long but smooth DAO trigger for this style of carry. The PM9 is legitimately small enough it can be carried inside a holster, inside the front pocket of a pair of Mens' jeans. The XDS can't claim that same feat, which ultimately disqualifies it from my consideration. The whole pistol is pretty well melted/dehorned and is great in the pocket. The capacity of 6+1 with Winchester PDX1 124gr +p provides entirely adequate firepower. I've chono'd these and they go over 1220fps from my pistol, and that provides an honest to goodness 400lbft+ and somehow, the pistol shoots them smoothly and while a little snappy, it is entirely shootable. I've also fired the Kimber Solo9, the Keltec PF9 and maybe a few others...none of them shoot as smoothly (or even close) as the Kahr. No idea why, but it's true.
People complain about the long DAO trigger and I'm not sure why. No, it's not a 1911 trigger, but it's really functional and easy to master. I often take my PM9 to shoot plate racks and I'm generally able to clean the rack @ the standard distance (55ft?) in about 6 seconds starting from a low ready. The trigger is smooth and has *no* stacking whatsoever.
The downside to the PM9 however, are that it's got a couple of quirks in regard to putting cartridges in battery. PM9s want you to use the slidestop to release the slide and let is slam home. Many will jam if you just pull back on the slide a little and release. Most will jam if you put a magazine into a pistol with a closed slide, and then try to cycle the slide. The owners manual mentions this, and I've found it to be true with mine. If I use the slidestop only, the pistol has never malfunctioned.