Well I know people who do this "(:" just because when they do this "" a weird looking emoticon shows up. It doesn't really matter on which way you do it.
I usually write , because I do the eyes first. Starting with the mouth just seems.. unusual^^
Another smiley question: why do some use and some =)? I saw the =) a lot around in Runescape and used to do it for some time, until I got used to , dunno why.
I use both whenever I feel like it. But the weird problem I have is that I hate when a text smiley turns into an icon. I just hate it. Text smileys look so much less cheesier and icon smileys ruin a sentence. So mostly I use :] [:
I use neither - I consider your more mundane smilies - ie, (:, to be nothing more then a joke when it comes to expressing yourself - I only ever go with /D: or :3 - all of which is single meaning and use. It makes life a whole lot simpler when it comes to smilies.