I'm with Savage, too.
After reading piles of opinions on the subject that were all over the map, I came to the conclusion that it couldn't possibly be that important, or there would be some semblance of consensus. (Compare to what people say about chain tension, for example, which is basically uniform advice across the board.)
Some people worry about potential interactions between additives in different brands of oil, perhaps reducing the effectiveness of the oil. I've not seen an actual, tested example of that, however.
I bought a spare quart at a moto shop a while ago. They had known brands, and then also Kawasaki and Suzuki branded oil. So I asked which was cheaper, and they were all $4.99 (probably because they were all the same oil, I'd wager.) So of course I bought a quart of Kawasaki and my friend bought a quart of Suzuki for her DR-Z400SM.
But who knows what will happen when I put that in with the Valvoline I have in there now... Maybe they'll fight!
The only thing people agree on is that you should change your oil every 3000 miles; some people go 6000 on synthetic. And that you should change your filter every other oil change; some people do it every oil change. And that any oil is better than low oil.