For all weather camping (presuming you're talking the colder end of the spectrum):
A lot of people swear by freestanding tents, but I've never found them to be that big of an advantage and IMO they're not worth the extra weight/bulk. If you learn to make "deadmen" from your kit/stones/sawn up branches for most 3-season tents will work fine in all snow that you could still ride in. Large nails made into pegs for frozen ground are similarly useful if there is unlikely to be thick snow, but the ground will be frozen.
In terms of specific brands, Exped 9 DLX is a superb mat for winter camping. Really worth the minimal weight/size penalty for the warmth it gives. A good sleeping bag is a must. A lot of people swear by down-filled bags for very cold weather. Generally I'd agree, but I prefer the Mountain Hardware Lamina range. They pack down as small as equivalently warm down bags, yet retain all the advantages of synthetic. Until recently, they didn't offer models that go down to *really* low temperature ratings (although a colleague still managed to use the Lamina 0 on a successful Kilimanjaro ascent! They aren't "cheap", but they're about half the price of equivalent down bags too! Only slight disadvantage compared to the real "money no object" down bags (that have a waterproof outer layer to keep the down dry) is a slight weight penalty. Weight isn't as a big a deal on a motorbike as hiking, IMO.
For a camping pillow, the Exped inflatable pillow is the best compromise between pack size:comfort/a good sleep that I have found. It's smaller than fist sized packed up and weighs nothing.
It's more important than usual to take an emergency orange bivvy bag and space blanket when you expect it to be cold. Between them, they can add a few degrees of warmth if it's colder than expected in your tent/bag and will usually ensure a basic level of "survival" if your tent and/or sleeping bag are damaged/lost.
As cchoc says, Jetboils are great. I've never had problems with the gas itself in cold weather, but the piezo (lighter) that is built in stops working at high altitude/in really cold conditions. Carry a firesteel/bic lighter as a backup. Dehydrated food makes more sense in cold weather where snow/water is more prevalent. The weight:calories ratio is great too, which is really important when it's very cold (as you'll burn a lot more calories). There's a particular brand I use for cold weather (comes in orange packets) that are about twice as calorific as the next competitor. Damned if I can remember the name now and I'm overseas so can't check, but will edit this post if I remember when I get home.
Testing winter kit before you need
it is ten times more important than summer stuff. Try it out in your yard, or within 10 miles of home before using it in anger. When it's several degrees below freezing at high altitude, in a foreign country, in the pitch black and you have damp clothes is not the time to find out you don't know how to put your tent up, or that your optimistically categorised "four season" bag has only been designed to withstand the rigours of a Jamaican winter.