I never use legendaries in-game, and unless the world will end if I don't I will continue this. First of all, the game just isn't as interesting for me, using a legendary. It becomes a bit too easy and more boring. The Elite 4 never uses legendaries, and for me, I would only use a legendary if they had one also. Second, legendaries don't appear until later in the game, which is another turn-off for me. I prefer to use a team that I have developed a lot over time, and I also love that feeling when I evolve a Pokemon to its last form, making it "complete" in my eyes.