Bright has a good opportunity to get upstate votes, while Mace can gather support in the lowcountry. Bright can also get far more evangelical votes than Mace can. Cash will probably also bring in more anti-Graham votes.
One will be eliminated in the first stage of the primary. The most successful candidate, which I believe will be Lee Bright, can beat Lindsey Graham as all the anti-Graham vote will go to him in the runoff.
The Texas Senate primary had around 10 candidates, half of which had Tea Party links and support and a few others being strong social conservatives. The supporters of all these candidates rallied around Ted Cruz in the runoff, giving him a strong 13 point victory over the establishment candidate.