I own both and enjoy both 357 magnum revolvers and 9mm glocks.
The way I look at it is they are both pistol calibers. The difference between the terminal ballistics is not very significant. The biggest difference is in penetration of the heavy 357 magnum loads.
I carry the 9mm glock most of the time because it penetrates effectively for self defense, has great capacity, and carries easily. I may choose the 357 magnum revolver when penetration is more important than capacity, such as woods carry.
I shoot both calibers with about equal accuracy but it's easier to shoot the 9mm faster obviously.