Although I would of course always endorse Canon (), I am of the opinion that the impact on picture quality these days is as a result of a) the photographer b) the lens c) the camera...in that order.
This is why I, with my 40D, plan on building up my collection of good quality lenses and improving my photography with those before I even consider my next body. I'm happy with the Canon system.
So, I would also advise you to get the lenses you would like first and just wait for the new model rather than switching systems.