I'm going to make this short and sweet:
A Glock 19 with a Blackhawk Serpa level 2 holster will do you just fine. Now in my opinion, paddle holsters are quick and convenient, but it kind of kills the point of it being a retention holster if they can theoretically just grab your holster out of your pants. I wear mine with the belt loop thingy, but to each his own.
If you're looking for something a little more oomfy when your booger flinger catches the bang switch, and you don't mind paying twice as much for ammo, I'd go with a Glock 21SF, and no I'm not joking.
Glock 19 Pros
- Easy enough to conceal, big enough to be considered a duty weapon
- Accurate
- Reliable
- 15+1 capacity flush mag, 17+1 with a +2 extender or Glock 17 magazine, 19+1 with a Glock 17 magazine with +2 extender...extenders can be found for around 10 bucks, and will fit on your .40 and .357 SIG mags too
- Very low felt recoil
- Easy to field strip and clean
- No extra switches, levers, or flux capacitors
- Gen 3 and newer can mount lights
Glock 19 Cons
- None...at all...if you think there's anything wrong with this firearm you need to re-evaluate your life
Glock 21SF Pros
- Puts half inch holes in bad things
- 13+1 capacity which is pretty damn good for a .45
- Gen 3 and newer can mount lights (I think all SF's are at least Gen 3)
- VERY low felt recoil...in my honest opinion it has lower felt recoil than a Glock 19 9mm with standard pressure loads. This opinion is also held by my buddy at St. Pete PD which just switched to them from Glock 22's, and my buddy who is at De Soto S.O. with a G21 duty weapon. It almost defies physics how soft it shoots...definitely 125 lbs fiancee material.
- Accurate
- Reliable...why am I even saying it's accurate and reliable its a frickin Glock
- blah blah blah
Glock 21SF Cons
- Much bigger than a Glock 19...THAT being said... I have baby hands. I mean freakin tiny. It's sort of embarrassing when girls say "OH MY GOD YOUR HANDS ARE SO CUTE" and proceed to compare your hands to theirs. If you employ a proper grip, you and your fiancee will have no issues firing the 21SF. I've also fired a regular 21 with no issues.
- Good luck concealing it unless you're wearing a dress and ratchet strap it to your inner thigh
TL;DR version:
If you are looking for a great home defense gun, you can afford to pay a little more for ammo, and open carry is legal where you live, buy a Glock 21SF bro. All day. I miss mine dearly. If you don't believe me about the felt recoil, ask anyone here, or better yet go rent one at a range. It's unbelievable.
If you can't afford to practice with .45, or being able to easily conceal or not is a deal breaker, get the Glock 19. They're both great guns and you can't go wrong either way. Oh, also forgot to mention, a lot of people say you'll shoot yourself and you're an idiot if you use a Blackhawk Serpa...practice proper trigger discipline and keep your index finger along the receiver of the weapon and you won't have that problem. Everyone who says they shot themselves with a defective Serpa and it's dangerous is an idiot and shouldn't be trusted around firearms.