Individually, I prefer odd numbers. 13 is a much more pleasant number than 12 or 14. But I do like the even numbers when they're listed out. 2, 4, 6, 8, 10. It's a good scale. Using multiples of 5 or better yet 10 for settings and such is a given, though. When I'm at an item store in an FF game, for example, I like to even out the numbers of items I hold by buying or selling as needed.