First of all what is your budget? If defense is a use and you are considering a glock 17 reconsider and get a 19. Better suited to carry but you can still attach a light to it and keep it on the nightstand at night. And you can use G17 mags in it. 9mm ammo is cheaper than .38 special and anything smaller is inadequate.
My top picks would be a G19 or a 9mm M&P, preferably used to save on cost. After that would be a Smith SD9, ruger P-series, a German-built Sig, or Beretta.
If you get a revolver stick to Smith&wesson, Ruger, or Colt. .41 magnum, .44 special, .44magnum, and .45 colt get expensive so hold off on a wheelgun in those calibers until you can reload. Stick to a .38/.357, 9mm, or .45acp revolver.
I don't collect guns, I accumulate them.