The best way to decide which DSLR to buy is to first understand that you're entering a marriage. You will be marrying into a family. Hopefully, it's a large family. It really is that kind of long-term relationship.

Each camera manufacturer fits its camera bodies with different mounts. Nikon's lenses won't fit Canon's, which won't fit Olympuses, ad nauseum. It's like ink cartridges, laptop batteries, or any of number of "one size fits few" products. Once you own more than one lens, it becomes very difficult to change brands.

The little secret about cameras is that the body is the least of your ongoing expenses. As you gain expertise, you'll want more lenses for more flexibility. And it's tough going from a Canon to a Nikon, if that means changing all your lenses too.

It's very much like choosing which side of the bed to sleep on. You and your significant other make that decision your first time together, never thinking the side you choose might be your side for the rest of your life.

I think the best strategy is to scout out available lenses, determining those that fit your needs and budget... OK, first budget and then needs. Use that info to qualify or disqualify makers of camera bodies that interest you. And don't be afraid to qualify and then buy a camera just because a friend or relative also has one by the same manufacturer. Lens swapping among friends is a beautiful thing.