Asking what's the best holster is like asking what's the best tractor. What works great for one person or situation would be a disaster for another. Things such as holster material (leather, nylon, kydex) carry styles, inside the waistband, outside the waistband, open topped or snap closure, high rise, small of the back, as well as different body types etc. etc. There are just too many variables.
Having carried daily for over 35 years, both on duty and off, I would NOT recommend a crossdraw as a concealment holster. Not only does your holster have to secure your handgun to your body, but it must be accessible for a smooth draw while wearing clothing over it. It doesn't do much good to carry it if you can't get to it when needed.
Go through the motions of drawing your weapon from under a jacket or long shirt or whatever you would wear in a normal carry situation to get some idea of what will or won't work. My preference for my purposes is a strong side high rise that holds the weapon as close to my body as possible. It's not really concealment if you're printing (showing a bulge from the weapon).
I expect this will be a long running thread. Good luck.