I have three kinds in my refrigerator right now...regular, low-fat regular, and soy.
The low-fat regular egg nog has about the same amount of fat as the soy nog actually. I like both. At first I was drinking the soy nog a lot more because I couldn't find the low-fat regular. So my choice was full fat regular or soy. But yesterday I found the low-fat regular...so that's what I'm drinking mostly now.
Soy nog to me tastes like egg nog but with a soy-ish after taste (imagine that!). It's not a bad thing if you like soymilk, which I do, but it's definitely got a small bit of soy flavor to it (really small).