Hello,
I think nobody answered you because there is no actual response to your question since it's a matter of taste.
Myself, I have both installed but I rarely use vlc because I like smplayer more: the un-intrusive GUI, the ASS subs support (see the screenshots with the nice shadow on the website), the interface auto-hide and not covering parts of the screen, and the things I can configure to mplayer (the actual media player) while vlc does not allow me that without lots of hassle.
So I would suggest you to install it, play with it and choose for yourself. Remember that SMPlayer is an interface to mplayer so you-ll have to learn a little bit about it too.
Read about the pro's and con's here:
http://lifehacker.com/5866656/the-best- ... -for-linuxCheers.