Choices ....
In the $800.00 & under category you have a few picks;
The Ruger SR45, the PX4 Storm C(constant action), the XDm, the XD mod 2, Glock 21 gen 04, Glock 30S, M&P mid size or full size(with or w/o ambi safety, no magazine safety), SIG Sauer P320 or P220R DAK, P227R C3, Kahr.
To add night sights like TruGlo FTX or Trijicon HD is worth it.
As for defense or carry .45acp loads; I'd look at Corbon DPX, Hornady Critical Duty, Federal HST 230gr +P JHP, Ranger T T series 230gr JHP +P, Liberty Ammunition Civil Defense, DRT, Winchester PDX1.
I use Ranger T/T series 230gr +P JHP and Liberty Ammunition .45acp in my Glock 21 gen 04. I had MagSafe SWAT for home security but I shot it up & got the potent Civil Defense .45acp. I like it so far. It's light but fast with a high KE level. I use the Ranger T/T series for security work & CCW. It works well for things like auto glass/metal or common barriers(wood, clothing, plastic, etc).