Eh a few years back Canon were top for camera bodies - these days its Nikon - another year it could be Sony or Pentax or Canon again. Camera bodies, even the top rate DSLRs are disposable fast changing parts of the setup (at least compared to parts such as tripods, flash units and lenses - ie eveything else).
In all honestly the differences are more marginal than many like to suggest, yes Nikon has an edge, but its just an edge it is not a night and day difference (if it were Canon and Nikon would not share near equal divides of the majority of the camera market between them).
What should drive your choices are your intentions. Your budget, what you want from the camera, what you hope to take pictures of, what kinds of situations, subjects etc.... You have to put your criteria on teh table, only then can you honestly compare the specifications and the offerings from each system on offer to choose the one that will best suit your needs.
If you've really not many criteria at all to put on the table then either brand is about equal, there isn't a single subject or situation where one brand can do something the other can't* so you will not be limiting yourself in any way by choosing either one.
Note also that 18-200mm lenses are great all in one lenses, however the massive zoom range that they cover means that they are very poor optically speaking. At the 200mm end they will be noticeably softer. They do have a purpose and if you're really not sure what you want to do with photography they can be a great choice to get a wide range of focal length experiences. That said I would warm more toward a regular kit lens supplied with the camera and a 70-300mm zoom camera. The combo will give you a bit more quality over a wider range of focal lengths, and whilst the 70-300mm still suffers from the softening at the long end it does give you a bit more reach and thus a bit more potential diversity to work with.
* the only major difference is that Canon has the MPE macro lens which is a highly specialist tool which very few people actually use. Even then the performance of this lens can be replicated with other options so, again, its still not a field of photography that is closed to Nikon (or indeed any other brand).