Perry sputtered out in 2012.
If he jumps in to the 2016 fray, the video of his memory lapse will be played ad nauseum.
Being an active governor, however, puts him points ahead of anyone from the Senate, especially, and House, secondarily, Christie or Jeb Bush.
Cruz could be a force and Rand Paul will be a force. This time I am hoping conservatives will not split their votes and decide early on Cruz, Paul or Sara. I think it very unlikely that Sara will run so we need to decide on either Cruz or Paul. Either one is fine with me. Both are strong principled conservatives that can articulate the conservative message. Slight edge to Cruz on being the better conservative but slight edge to Paul on experience and organization. (And there is always that natural born citizen thing that could prevent a Cruz run).