You are comparing two totally different pants - you might as well ask if you should drive a Ferrari or a Land Rover
The Spyder is not 'more' of a ski pant it is the epitome of ski pants. Don't get me wrong - it is a GREAT pant. It is insulated, has super weather protection and the suspenders are great. It has a narrow fit from Hip and Leg down to the ankle - this is IN these days in both ski and snowboard but you have to decide if you like that. It is made in a mechanical stretch fabric so there is give and it is not atight
fit, just narrow.
The Burton is a Gore-tex product, it is a 2 ply shell with waterproof zips - also a top of the line for waterproofness but has a baggy fit - not huge but more of the traditional snowboard cut. Keep in mind, it is just a shell.
To make a good decision you need to think about how you are going to use the pant - what conditions do you REALLY find yourself in and consider the style you like best, what suits your personal taste as well as where/what you ride.
Both pants are great quality, you won't go wrong with that - good luck!
See ya on the slopes!