Simply put: Layers.
And buy good stuff as if it's taken care of, it will last for years. Most of my winter gear I bought when I first started mtn biking back in the early 90's. IMO, it pays to have a lot of choices for a given weather situation.
I have an old pair of Sidi winter shoes. I've had to glue the soles back on, but otherwise, they still work and I see no reason to replace them. They were expensive when I bought them ('93?) at around $130.
I have many pairs of socks from tele-skiing. In general, if my feet are comfortable, I'm comfortable... and vice-versa... everything from there depends on how much standing around I'll be doing. I'll dress differently for a straight XC ride than I will for our annual Christmas ride through Philly, which usualyl involves a lot of stopping, standing around in the cold... and adding antifreeze...
For gloves, it varies... and I'll often stash different options in my pack. Oddly enough, I often just wear my Fox full-finger DH gloves that I normally wear the rest of the year... and keep a pair of glove liners and ski gloves in my pack.
Oddly enough, I don't think I own a single pice of Goretex... not sure why... I've lusted over it in the store... but just haven't had the need, yet... and I've ridden in some pretty cold conditions (zero F + wind at Jim Thorpe one year).
In the end, everyone handles the cold differently... so what works for one person may not work for others. And because the conditions can vary in temperatures, wetness and wind, there really isn't a "one-size fits all" solution.