IMHO, night sites alone are over rated. I want something to draw my attention to the front sight. For a carry gun, I love the Trijicon HD XR. For range use, Dawson Precision.
I just throw sights on mine and shoot the crap out of them. If it was a competition gun or something I didn't carry I would consider a stipple to roughen it up, or try and get my hands on a RTF2. Otherwise I leave them alone and they work for me.
My brother has a "tricked out glock" which is great if you spend a bunch of time shooting it too. However, if he had spend equivalent money on shooting it he'd be a much better shooter. Upgrades help, but not as much as your skill *humble opinion* I'm not good enough to see full benefits of something all slicked up yet. A slicked up gun in my hands wouldn't pay the dividends it would maybe in some else with more skill is what I'm getting at.
I put night sights, Vickers mag release, and ghost slide release and call it good, some have ZEV connectors but I can't notice much of a difference with a factory connector.
I always keep them box stock and put my time and money into ammo and range time. IDPA or similar to shoot under more realistic conditions. It's amazing how different it is shooting under a little pressure than just putting holes in paper.
Double diamond 3.5lb connector, titanium coated safety plunger, and I leave the factory springs in the gun. Xs big dot sights, 8 mags, I might have 10 holsters, 4 mag holsters. 2 extra barrels and a reloading press or three. Mag release and slide stop I changed and went back to the factory ones. As mentioned above shoot it before you change anything. I wasted money on the slide stop and mag release could have bought a couple more boxes of ammo at Walmart.