Was there a specific name you wished you had when you were a kid? It might feel more "you" if you know you always wanted it. For example, almost by complete accident, Alex is a name I wanted when I was younger, and considered trying to get everyone to call me that, but no one played along. My middle name, Luke, is also something I told people was my middle name when I was even younger. I completely forgot about both these things, but after I chose my name I remembered, and I felt a lot pretty certain they were the right names for me.
I had a similar thing with initials, I wanted to have a name which started with an 'A' because of my birth name beginning with a 'Z' (the name that I ended life pretending to be a girl/alphabet on, and then name I began afresh on). At first I went by Adam, but stuff happened, and I had a niggling feeling that I wished I'd picked Alex. I went through a short phase of using Alec, because my ex was going by Alex at the time, but I got over that, and felt that Alec was too foreign for me anyway.
As for changing your name on here, I dunno if anyone mentioned it already, but you can change the name everyone else sees, just not the one you log in with. So you all know me as "AlexanderC", but the username I put in the sign in box is "AdamMLP".
EDIT: Matt's what I would have been named by my parents, and a potential extra middle name, so I like it. If you're worrying about a name getting out of date, chose a name that was popular in your birth year. Mine are by accident, but if you called yourself something popular at the moment (the only thing I can think of is the Trans "stereotype" of "Ayden/Jayden/Kayden/*den") you might stick out like a sore thumb. I like the name Scott, but it's too old for my generation, like Steve is actually. Or Dave (I used to get called that a lot because I try and fix everything, and apparently it's a handymans name lol)