Just my input from a reasonably new gun owner (1 yr):

As far as type of weapon selection goes: I have a small 9mm semi-auto for concealed carry (a Taurus PT709 Slim). I have a full frame .40S&W semi-auto in my car in a seat holster I made myself (Springfield XD40 5"), and a tactical 12ga shotgun under my side of the bed (Benelli Supernova).

Those three weapons suit my needs for the location that I expect to need/use them in. Again, just my personal preference.

As for choosing a specific make/model:
You generally can't go wrong with most any modern and some older (1911 for example) guns, be it a pistol or shotgun. The ability for the user to manipulate all of the controls on the gun without much fuss is important, as well as you know, just the general comfort in your hand.

I happen to like Springfields XD and especially their XDm line of pistols. If you get the chance to try an XDm9 4.5", do so. It is a very nice polymer framed firearm with a very high capacity magazine (19+1).

Most important of all though is your proficiency with your particular firearm. Whatever you end up buying, practice with it as much as you can afford to. Operating the gun in normal operating circumstances and during various failures needs to be as close to muscle memory as possible if you intend for it to be the gun that may save you or your loved ones life. Flying your airplane once every couple of months isn't going to prepare you to handle an in-flight emergency very well, right? Same idea here.

What has worked well for me, is I participate weekly in local practical pistol shooting competitions. I don't do it for the sake of competition, but for the fact that every week, I learn useful information from the very experienced shooters that are there, and the competitions are a much more practical experience with your firearm than simply standing in a bay shooting at paper. I can say that my proficiency with my pistols has improved considerably since I started participating in local competitions in both my ability to quickly and accurately engage a target and in my ability to handle failures of my firearm under simulated stress. I've not yet become a pro by any means, but my improvement has been noticeable and it has been a great training tool. Just something to consider.