Now, if it is to be an action figure, then let's be practical. That is how I came up with the "Captain Kathryn Janeway as seen in 'Flashback'" ("Voyager") figure all those years ago (1999), when a mail order firm, NewForce, commissioned an exclusive Playmates figure.
An exclusive collectible action figure needs to make use of some existing Star Trek figure parts, where possible, to be cost-effective, or be so highly-coveted by a group way beyond the usual core of action figure collectibles. The Official Star Trek Fan Club 4.5" Captain Mackenzie Calhoun was the star of the Peter David "New Frontier" original novels, at the time (and still?) Pocket Books' biggest-selling ST author and series. The Official Star Trek Fan Club 12" Romulan Kirk figure was a bigger risk, with its all-new head sculpt and tailored cloth clothing, but a very impressive Kirk figure. Janeway was a captain and very difficult to find at retail and, while all other TV captain had multiple figures, there'd only been one previous 5" Janeway - so a "Flashback" Janeway using TOS movie body parts (indeed the female ST II-style uniform, which had only ever been used on the hard-to-find Saavik) was sufficiently collectible.
When Art Asylum took over the license, the New Force Charles "Trip" Tucker in Starfleet uniform figure was also a no-brainer headswap for a popular character that extended the "Star Trek: Enterprise" range. However, the dismal ratings of "Star Trek: Enterprise" - and Travis Mayweather's dismal, tiny part in the series, would see the rejection of a planned Mayweather w/ console following a lack of retailer support.
The upcoming buzz is that the next Star Trek movie is a Kirk & Spock movie. Spock/Nimoy would be THE most popular character to the wider ST community. ST fans who weren't into collecting ALL ST figures might buy a single Spock figure if it's sufficiently cool.
So... assuming a current-style Art Asylum-created action figure, and using an existing head sculpt, what about barefooted Genesis-resurrected Spock in cloth burial robe, as seen in "Star Trek III: The Search for Spock", or add optional black trousers and boots and you have Spock in meditation robes from "Star Trek II: The Wrath of Khan", or or add grey, pleated trousers and boots and you have Spock in traveling robes from "Star Trek: The Motion Picture"? Or give him a cloth white hooded robe and headband you have resurrected Spock from "Star Trek IV: The Voyage Home". Anyway, that'd be my pick.
Speaking of resurrections: The Official Star Trek Fan Club's biggest resurrection hurdle won't be an exclusive for members to be tempted into buying, it'll be winning back the confidence of a lot of its members after Decipher's mishandling of the magazine "The Star Trek Communicator", and the lengthy delay that's allowed Titan's "Star Trek Magazine" to fill the void.