I post as myself 99.8% of the time.
I figure people listen to someone they 'know' better than somebody with half a dozen posts who hasn't established any kind of rapport or track record or identification with other posters, but if somebody has something really worthwhile or interesting to say you're going to pay attention regardless what their user name is.
It's annoying to me when people post interchangeably as somebody else (or elses) and you don't know for sure who you're dealing with. Nobody likes having the wool pulled over your eyes after all or feeling as if they're being deceived.

With some it seems to be some sort of game.
However, there are advantages periodically using an alias. So there you go.