Mac Collins and Herman Cain are both very conservative, with VERY similar ideologies; you really can't go wrong with those two. There's quite a bit of time before the primary to see which one strikes your fancy. And if no candidate gets 50% in the first round (which appears likely) there will be a runoff, probably Isakson vs. Cain/Collins, where the choice will be easy.
andy1114's "Collins is definately the most conservative" assertion is totally baseless; he's a Collins partisan who's just woofing it up.
I am not sure how you personally define "most conservative", but I feel like the way to be sure is when there's a proven record of conservative action and votes. With Cain, we have very impressive speeches and positions that are terrific, but with Collins, we have over 12 years of votes to look at. I am personally more comfortable going with someone I know for sure has put his conservative principles in action, and that would be Collins. Also, I had never heard of Cain as doing anything to change the way things are when it comes to issues like abortion or tax policy until he announced for Senate. I along with many others have been working for years trying to bring about change by writing letters, making phone calls, joining political action committees on these issues. We'd like to have someone represent us who has also been working hard at these things over the course of time, not just recently announcing their interest in them. I'm glad Cain supports all these things, but I prefer a seasoned leader like Collins who has not only supported them all along but has also been doing something about it. Cain likes to say that he's the best one for the job in part because he's never held public office and that the other two candidates aren't as good because they are already in office, but he hasn't said that he would limit his time in the Senate to 1 term. If being in office is a bad thing and renders the office-holder unable to do a good job, it seems like Cain would apply the same reasoning to himself. Also, I think it's a mistake to presume that things happen overnight in Washington. Take Rick Santorum and the partial-birth abortion ban. For years he has worked to move that through the Senate and gain this victory for the unborn. But he couldn't do it alone. It took his tireless efforts along with getting more conservatives in the Senate to get it through finally, which is one reason Collins wants to be in the Senate, to help build the conservative majority so the Senate will stop holding up good legislation coming from the House. Just a thought. Anyway, I am going with Collins because of his experience and his record, which I have taken a lot of time to research.