I will mention some basic design differences between ZT and Spyderco. ZT makes BIG KNIVES. They are on the thick side, heavy duty to a whole new level, and overbuilt. They take up a lot of room in your pocket and fill your hand up. I liked my 0200, but eventually ended up selling it to someone in the family so that I could fondle it once in a while. I have never owned a spyderco, and so I can't comment. IMO, I love ZTs, and if you like the weight and size that comes with the toughness and solid build, then I would go for it.
Final note: the ZT warranty is bulletproof. You can do anything to them that a knife was designed to do, plus more, and if any part ever fails it is replaced no questions asked. they are very good about that.