Do you want this for a race .. or not?
If that's the objective the Zion is the better pick, especially with the spoiler addition (Felon is no slouch either but the nod here goes to the Zion). I do believe the Felon GT no longer has the edge over its' 4 door counterpart, the Felon.
If this is not for a race .. select which feels and looks better? If this is the case I would opt for the Felon because it seats 4 (yes this isn't an option, I don't like convertibles) and is the better looker IMO + has a few more customizations. They're both good cars though so if this isn't for racing purposes we are no one to tell you what to get.