The Nikon D200 looks to be a geat camera, in fact Canon really have to pull something out of the bag with the 20D replacement to stay in contention at this price point. If you're a first time DSLR buyer and you've got the moolah, it's the one to go for without a doubt, but it will do absolutely nothing to improve your photography if you currently use a 70D.
Bodies come and go as Steve said, but good glass is with you for a long time, and will drastically improve the options you have in the approach to your shots, and is capable of making a really significant difference to your work.
