Most of mine are from the early days of the license, aka The Good Days, rather than from the disjointed 1996 and later era when the line lost focus. In no particular order, here are mine:
1. Esoqq -- a mysterious figure and a mysterious alien, one that was underproduced due to low expected sales. Yes, weird aliens got shorter production runs, and Esoqq is about as weird as they get. These could be $80 back in the day.
2. Red Data -- a legend back in the day. The first true chase figure, and made doubly so by the whole Redemption error. I saved up $300 to buy mine in 1997 via mail from a shop that advertised in Tomart or Lee's. That was a BFD, as our former vice president would say. Hashtag priorities!
3. Thomas Riker, TNG -- one of the first true chase figures that was hoarded by scalpers bigtime. I still love buying these, esp in Canadian packaging. I remember these advertised for as much as $280.
4. Odo from Necessary Evil -- Odo was an early fave of mine, and this figure is still very nostalgic. I remember there was big anticipation for this wave of figures: Dax from Blood Oath, Sisko from Crossover, etc.
5. Nausicaan -- just a well-done, big alien figure that offers fun packaging variations. Like Esoqq, this was an slightly underproduced "bad guy."
6. Chekov Generations -- the classic characters + spacediving Kirk I never even saw in stores, that's how fast collectors & scalpers whooshed them off shelves. I didn't get the first classic Generations figure till 1997 or something, and paid dearly.
7. Ambassador Spock -- this was kind of an uncommon figure back in the day, and the first one I bought was numbered #000141. People forget that the 2nd release had a total of 3 classic characters -- this was Playmates trying to attract collectors.
8. Tasha Yar -- It was nice that the manufacturer went back and did this figure, and the fact that it was offered on 7th season card in Canada is pretty wild.
9. Ferengi -- an early favorite, and probably the wildest of the first release. I think I paid like $20 for my first one, which had no black highlights on boots.
10. Metallized Locutus -- Locutus is already a cool figure, but this rerelease was a nice and eye-catching update. Together with the backer card, this is one of the sharpest-looking figures in my book. Also, he may have been produced in smaller numbers that some of the others in that wave. It certainly seemed like that back in the day and it seems like that now.