I own a shield, and have since they came out. The G43 is enjoyable to shoot. I don't think you can go wrong with either. You can pick up the shield for less money though.
I was rereading this thread and on a different thread, I traced my journey on buying the Shield 9mm for $280 and even later bought a Shield 45 for $320 w/$100 worth of ammo included.
I am enjoying the 9 and the 45 both and will sell one or the other, probably the 45 since I don't need that large of a caliber, but for the right price, I'd buy anything.