I used to always use the Pilot Hitechpoint nice to use and you can also see how much ink is left. At school, it never used to be a problem, but at uni I was going through two or three over an exam season with heavy essay content, and you don't want to be left without.
A word on the traditional bic pens - you have to press a lot harder on the paper than with something like the Pilot / Uniball, which over the course of an exam session (if you are doing essays) can be very tiring on the hands / arms. This is apparently why fountain pens are supposed to be better for you (as you don't have to press down at all), but in reality the smudge factor is going to mean you'd be crazy to use a fountain pen in an exam nowadays.