I like the Safariland over the SERPA because it (IMHO) retains the weapon better. The suede lining also protects the gun finish better and makes it difficult for anyone other than you to remove the gun from the holster. Its easy to draw it up and out, but if your trying to pull it out from the side, its much more difficult. Not that big of a deal in airsoft, but handy feature none-the-less. I also think the Safariland drop leg platform stays in place better than the Blackhawk one. The Safariland holsters are a bit tighter than SERPAs which can be a drawback as they can cause the slide to move when your holstering your gun, but of the 3 that I have, it hasn't been an issue.
Also, FWIW, Safariland makes a holster for all the pistols you mentioned, including the Mk23.
Before you decide to go down either rode, test drive both holsters if possible. The action for releasing the Safariland is much different than the SERPA and can throw people off under stress.