When you say you have yet to hold any gun, do you mean you have never held or shot a gun? Or simply yet to hold or shoot any of the ones you mentioned?
Based on some of what you have said and asked, I would highly suggest taking a handgun course or going out with an experienced shooter that can bring a long a couple different ones for you to try out, get some good guidance, and experience with.
Simply put, I would say yes, you are reading and thinking way too much, and just need to get out and shoot some of these guns. You will quickly find which ones you like/have a much better idea of what matters to you more so than a youtube video or some random person's opinion on a forum.
As for the guns you mentioned, they are all excellent. I am a big fan of XDms myself, really like the way they feel in my hand and the way they shoot. Glocks are great guns, as well, very durable, reliable guns (I am not a big fan of the way they fit my hands, but others believe they are perfect). Both are very safe to carry, even though neither one has a traditional safety, they both have safety mechanisms (Glock has their trigger safety, XDm has both the trigger and the grip safety).
I will stress this big time, though. From the sounds of it, you are a long ways from being in a position to even think about carrying, and should spend your time focused on learning how to safely handle a gun, shoot it proficiently, and build the skills needed to safely and competently carry.