This is a tough one, but I'd probably say Tarkin as well. Though the RFT, Sandtrooper, Han Trooper, Slave Leia, Oola, and Yarna would've all been excellent choices as well...
What's kind of a bummer, is that I spent a lot of time on the convention circuit in the late 80's/early 90's running around buying up expensive and very well done custom jobs of all of the aforementioned missing vintage figures (including other like Garindan and Ephant Mon), to round out my Star Wars figure collection. We're talking some pretty good dollars on a lot of these.
Needless to say, I had no idea the modern line was just around the corner in '95. Pissed me off something fierce all the money I wasted on these, when there would eventually be some real nice versions in the POTF2 era and beyond.
Oh well.

I'll have to put a shot up soon of some of the vintage customs I bought back then. Cool stuff still...