I have a fountain pen with a nice broad italic nib. The line variation (thick downstrokes, thin horizontals) makes my ugly handwriting look big and bold.
Paper is cheap so I don't hesitate to write large (helps legibility quite a bit).
I get lots of compliments on my writing - perhaps it compensates for my idiotic notes.
Black ink, because it's required where I am.
As an aside, when I was in Japan, everyone used those 4-color pens. They had a system - red for the most important points like med changes and abnormal labs, blue for instructions given to patient, and a few other things, etc. It made the charts much more accessible at a glance.