As someone who used to 'hang out' with a lot of different characters, I would say that the clickable sharpies would be the best. Nice fat barrel for them to grab and easy to click if you forget to do it for them - always make sure your writing instrument is ready for the characters and ALWAYS hand them the non-writing end of the pen first. That last part helps you not write on their hand (such a faux pas) and they don't have to fumble with turning them around to write with.