3. "The Space Pirates"
I'll be honest - there's a part of me that's surprised to be including this so high in this list. "The Space Pirates", despite being written by Robert Holmes, arguably one of Doctor Who's greatest writers, is one of my least favorite stories from Patrick Troughton's era.
It's a story that moves at an extremely slow pace and has some very forgettable characters overall. The highly eccentric Milo Clancey is admittedly an exception to this, and foreshadows some of Robert Holmes's much more successful characters like theater impresario Henry Gordon Jago in "The Talons of Weng-Chiang" or traveling showman Vorg in "Carnival of Monsters".
But Clancey's not enough to carry the full story, especially a story that feels far too long at six episodes. It's funny, because the next story, "The War Games", is four episodes longer, and yet feels like it moves at a considerably faster pace.
So why am I rating "The Space Pirates" in the top three likeliest stories to be animated next? For one thing, because it is such a simple sci-fi story - frustratingly so, at times - it should be easy enough to adapt to animation.
On top of that, "The Space Pirates" is the only clear gap in Season 6. The only other story in the season with missing episodes - "The Invasion" - was completed with animation back in 2006. Right now, no seasons of Patrick Troughton's era have been released as part of Doctor Who: The Collection, most likely because each of them still have clear gaps. With "The Space Pirates" being so potentially easy to animate, it would make Season 6 an easy season of Troughton's to finally release.
Having said that, Season 6 isn't the only season that needs one story to be animated in order to be "complete". But we'll get to that in a moment.