I use Syaoran because it's the original way to spell it. "Syaoran" was used in the Manga before "Shaoran" was used in the Anime. Spell it however you want, if you have only seen the Anime, go with "Shaoran", if you have only read the Manga, "Go with Syaoran. If you have seen and/or read both choose which is more natural to you. I, personally, have always liked "Syaoran," so that is how I spell it. Spelling doesn't really matter anyway, as than as you use one of them and people understand who your talking about.