An over-aggressive driver, or a timid driver?

I ask because I'm not too sure myself. Sure, the over-aggressive driver is probably going really fast and swapping lanes really quick, but attempting to merge onto a highway when the speed limit is 100 km/h and the person in front of you is doing 60 is also pretty dangerous.

So, which is worse to you?

Have a Subaru from my hard drive for your time (no, not my picture).

Which is worse?