I like the simple interface of MPC. As mentioned I use MPlayer most of the time. By MPlayer I mean MPlayer not KMPlayer or GMplayer or some other GUI'd MPlayer, just MPlayer.
For videos I only need my keyboard when playing, and a settings file.
As for music player interfaces, I don't understand why they have gotten so bloated. foobar is very nice, and in Windows thats what I use.
On the subject of Nanami-chan, I haven't gotten tired of her yet. The "chin" is annoying, but only because so many programs seem to close at strange times.