Wow, no pun intended, that's a loaded question!!!
Since you say "without a safety", and there aren't too, too many traditional double actions with 1911 safeties, but there are some, it becomes very subjective. A Chief's Special pistol, if they still make them and I think they do in 9mm, is an amazingly great little gun for concealed carry. If you love the S&W decocking system like I do then you're bound to like the "CS" pistols.
It's not like you can't carry a service sized pistol concealed. I rarely do it but I did carry a SIG SP-2022 (9mm) OWB under a "longish" vest for hours on Friday night and then again on Saturday morning. No problems. But the CS-45 would have been far easier.
So would any "smaller" S&W - there are plenty of 3rd Gen pistols that fit that bill. I don't have experience with the new M&Ps so I can't comment there but a 6906, for instance, would be great.
***GRJ***