Ok, if I could only own one gun and it had to be good for protection, range practice, camping, etc it would be either an S&W 357 magnum with a 4" barrel or a 5 round 38 special capable of handling +P+ loads and with a 3" barrel. A third possibility would be a 5 round 44 special.
As you can see I chose revolvers, this because you can leave them in a nightstand drawer for ages w/o worring that they will jam a year or two later. Autos are much more finicky and I do not want to worry about a gun malfunctioning.
Now about he 45ACP in a 1911, you will love it. Many say it kicks a lot, and I disagree. However there are some things you should know:
1. Backstrap comes flat or round. Depending on your hand one will work great the other not. I shoot better with the flat.
2. Ramp should be polished, otherwise certain hollow points will not feed right.
3. Ejection port should be made larger to allow for better ejection.
4. An action job to improve smoothness is needed.
5. Sights, adjustable for target or luminous for defense.
6. If you still have money left then a match grade barrel would be nice if you plan to use it mostly for target. When you start tightening the groups the gun may get finicky about the type of rounds you use and if needed for defense it might jam. So a match grade barrel or a rail system could undermine its usefulness as a defense weapon.
Hope this helps.
PD: Having a weapon for defense use is one heck of a responsability. Not only to prevent accidents with loved ones but also should you ever need to use it. Anyone contemplating getting one should not only take a weapon handling class but must be able to answer: Am I willing to fire at an attacker if I believe my life/wellbeing is threatened? If you can not say yes then do not get one. Just my $0.02