Which is the more radical group Sunni or Shi'a?

Which is the group that has more radical/extreme views?

Extreme according to whom?

I believe the Shia are the ones with the more radical views, however Sunni's are a bit more repressive because they have more power than the Shia. Or it is the entire other way around.

There is nothing inherently more radical in either group.

Most terrorists are Sunnis. However, the vast majority of Muslims are also Sunnis.

There are radicals in both groups, there are moderates in both groups. I second what Nightwind said, there's nothing inherently radical in either.