I don't think I can really pick one, though the names that spring to mind for me have already been named.
Eirc Young is a young guy that I think has a lot of talent. To me, he showed a lot of what he could do on the mic when he was leader of World Elite. He's got good mic skills and can be entertaining to watch inside the ring. Unfortunately, I have a feeling that Young is going to be mostly a comedy guy for the rest of his career in TNA. It's a shame as he does have a good deal of talent and I'm just over his brain damaged comedy stuff that he's been doing for so long now.
I also have to go with Chrisopher Daniels. He's shown real ability on the mic since going heel and we all know he can go inside the ring. Daniels is one of the older wrestlers on the TNA roster but he can still go. I know this might border on blasphemy in the minds of some but, personally, I'm kind of tired of seeing him feud with AJ Styles. I know they have really good matches, it's just that it doesn't feel the least bit fresh. It's becoming the John Cena vs. Randy Orton scenario of TNA in that we've seen them go at it sooooooo many times. It'd be interesting to see Daniels pushed further up the ladder rather than be a mid-card guy that's typically treated as though he's largely irrelevant with the exception of an occassional feud with AJ Styles.
Douglas Williams is someone that I've become a fan of when he went solo. Aside from Austin Aries, Williams is really the only guy in nearly 3.5 years to really make the X Division Championship relevant. Williams was a damn good champion all things considered, especially since the X Divsion had so little relevance in general during the time Williams had the title. Williams has shown good ability on the mic and also has a lot of ability inside the ring. Like Daniels, Williams is one of the older guys on the TNA roster and it's possible that time is running against him when you consider his age. However, Mark Henry has been a lesson that you really should never write guys off even if they're hovering around or are over the age of 40.
Another guy I'm going with is, beleive it or not, Bully Ray. Ray is someone I've never been overly impressed with inside the ring. He's pretty decent overall, with occasional glimpses of brilliance, even if his selling tends to stray over into the comedic realm at times. His mic work has been consistently impressive and he's gotten himself into really good shape, probably the best of his career. To me, it just seems like he's been too talented overall to waste on feuds with Devon or Abyss for playing the role of stooge for Bischoff. It wouldn't bother me to see Ray given a shot at the main event picture. It already seems a little crowded right now, however, with Hardy & Storm in the mix. For the time being, I'd settle for a good mid-card title run except that the X Divsion is for guys 220 pounds or less and the TV title is a joke and wouldn't do Ray any favors.
As for some of the others mentioned, such as Abyss & Gunner, I just don't really see it. Some probably will say the same about some of the other picks, different strokes for different folks and all that. To me, Abyss used to be moderately interesting years back but the Abyssamania era just really, really ruined the Abyss character as a whole for me. Gunner is a guy that I just don't see anything that stands out. He's not much to speak of on the mic, there's nothing at all special about him inside the ring, his "intensity" amounts to him slapping himself in the face a couple of times and he still comes across like a low level stooge that can't accomplish anything without someone helping him.