I used to go for ballpoint over gel because ballpoint would work better on duplicate checks. But the other day I was thinking about this and realized that I haven't written a check in like two years so I don't think pen type will matter to me any longer.

As for mechanical pencils-- I'm in love. I use them for everything, including art. (Well, now I use a tablet. But before the tablet, my mechanical pencil sketched many, many things.)