Your model looks nice, I like the slight bend in the wires holding the filament. The third render looks best in my opinion, since it looks most realistic (I agree with the previous poster about the IOR being too high on the other ones).
The glass looks slightly tinted, was that the way your reference was?
I am actually working on a lightbulb myself, am trying to render it with a glass layer on the outside with layer of phosphorus (or whatever the white coating on the inside of incandescents is), but it keeps showing up black (the depth is set high and I have tried scaling the whole bulb…who knows).
Your base material looks nicer than mine too