Is all Gore-Tex equal? Yes. Are all waterproof jackets equal? No. The numbers you'll see in outerwear advertising are the waterproofing and breathability figures i.e. 20k/20k. That means that the membrane itself can withstand a 20,000mm tall column of water without leaking and that in 24 hours 20,000 grams of water can evaporate through a one square meter section of the membrane.
So any 20k/20k jacket should be good, right? Unfortunately, waterproof/breathability numbers are about as useful as boot flex numbers, they don't really mean much. The main thing keeping your jacket waterproof is the Durable Water-Resistant coating (DWR). Companies like Gore have spent millions to produce the best DWR on the market. Whereas other companies boasting 20k/20k shells do not have the coating to keep their jackets properly dry. The DWR is so important in snow sports because of standing water (snow) build up on your outerwear. Snow is not breathable, so unless snow build up is diffused off the surface of the shell, the shell will not stay dry. Sweat will build up causing the jacket to feel damp and cold.
Is it worth investing in Gore-Tex, I think it is. It's expensive but it works as advertised.