Art Contest

I'm looking into hosting an art contest for my fictional short story blog; Dragon's Wife.  The idea will be to draw any of characters from any of the scenes.  I don't know yet where I'll host this exactly; deviantart or Facebook or photobucket OR Instagram?.  I have the top three prizes picked out (or maybe just one prize in case there's not a large response).  I debate on using the Facebook option.  Should I make a blog Facebook page for this to happen on then?

I'm really leaning towards people sharing their works via photobucket.  What do my readers think of this matter?  Feedback greatly appreciated for this.