The Glock 23 is my favorite. But I like all the 9mm and 40 cal Glocks. I bought an M&P 9C not long ago, and that gun is easy to love. But it is different. Smallish and heavy, it feels and shoots great. After about 400 trouble free rounds I have dubbed it the S&W Glock. Shoot the 23. I bet you will like it. Still, there is nothing wrong with hanging on to your 19. If the 19 is not worn out, I would keep it and save up for another model you might like. It's okay to have two, or even more. Selling one gun in order to try another is a road to eventual disappointment, IMO. You might regret it. The only really good reason to get rid of a gun is that you don't like it. Well, getting layed off is another one, but hopefully we will all avoid that, or at the very least step right into another job before the wallet is empty.
I own a Glock 23 and it's my CCW. I also own a Beretta 92FS. I'll take both to the range and shoot both guns. I shoot the 23 because I need to. I shoot the Beretta because I like to. The .40 cal is ,as has been pointed out, snappy. It seems to have a lot of muzzle flip(in my hands at least) and takes a bit longer to be back on target.