It's an extremely easy call if you ask me. Broun, a creationist with ties to the Paul movement, would be at serious risk a losing the GE to spawn of Nunn, so HELL no to him, I don't care what his fan club thinks about him being "the most conservative".
Grayson has a zero% chance of finishing in the top 2, so no to him, unfortunately he would be a wasted vote. I agree with you that Perdue is the least conservative, worse than the national GOPE favorite, Kingston.
Handel is the clear choice. Palin did us a big favor endorsing her, and Joni Ernst in Iowa. Despite what one poster on this thread thinks about Palin choosing to endorse women, they happen to be the best choices in these cases.
Karen Handel would be a difficult candidate for the ‘Rats to attack.