If you have that much to spend, check either the shotguns offered by www.wilsoncombat.com or go to a gun show and find yourself a Remington 11-87 Police Tactical Shotgun. It is a 12 ga semi-automatic scattergun that kicks surprisingly little.
As for loads, stick with buck for self defense duties. I like the Federal Tactical Buck load. It is fairly potent and has lighter than usual recoil.
As for 12 ga. I choose it because that's all Ive ever used, and it's easy to find at about any gunshop or rural hardware store.
Me..? I have an 1100 Remington with a deer slug bbl and the duck tube popped out so it takes six shots.
And I have a Glock 17, not a 19. It just fits me better. Back it up with a Kel Tec P-11 9mm.