ink color preference blue or black ink?

i use both black and blue ink but i prefer blue.

Depends on the purpose. Black ink on white paper seems a bit easier to read. However, blue marks on a black and white printed sheet -- like a form -- seems easier to pick out and read. Some might like the 'splash' of color blue taking away from the monochrome of the paperwork. I use any old color -- but I should probably use blue for the reason indicated above.

I also use black it because a job made us use it too and come to think of it I can't even remember the last time I used a pen with blue ink.

I use blue ink pens most often but I have a few black as well. It doesn't really matter to me I never thought I liked one over the other.