it depends lo. if you have number of friends playing this slr thingy might as well follow what brand they uses, so that u can share using the lenses later. otherwise if just for your personal use, i'd still recommend better go for nikon.
i'm thinking hard of changing to canon, cos of its 50mmf1.2 autofocus lens - which nikon doesn't have. but i love the dual SD card feature of my current d7k...so a bit of small conflict here.
but u might want to google over dpreview.com and cameralabs.com and make your final decision after that.
other ppl might have more constructive ideas than me, let's see what they have got to say.