In most cases, an autoflowering version will have lower yields & less power - it's because it has to be crossed with Siberian Ruderalis. This is a hardy plant from the extreme north that flowers after a certain period of time rather than being triggered by a certain amount of sunlight. However, Ruderalis doesn't have any psychoactivity.

In exchange for the drop in yields and power, you get a strain that usually finishes faster and is a little easier to work with.

However, some of the newer automatics are very competitive as far as yields and power go.

Check out Auto Bomb by Bomb Seeds & Big Devil by Sweet Seeds.