Yeah, I know, but Battlestar Galactica is #20, and also sounds interesting. I haven't played Twilight Struggle yet, no.
Hmmm...how to convince...
Well, one thing that's nice about TS (and probably explains its ranking) is that it mixes a lot of different elements together very successfully. On the one hand, at its core it operates like a card-driven wargame, with cards being played either as generic operations or to carry out specific events. Where it was innovative is that you often have to trigger your opponent's events in order to do things yourself, so high-quality play comes down to how well you can manage a neverending series of crises. In addition to being fun, this perfectly evokes the theme of the Cold War.
In addition to the wargaming elements, though, there's also Euro-style area control, a bit of deck-building, as well as some degree of bluffing/misdirection like in a traditional card game. All of this is done while integrating very well with the theme so that the game has a lot of atmosphere if you're a history buff.
Plus, as far as modern board games go, it's very good at mixing relatively simple mechanics with enormous strategic depth.
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SubDeity wants to vote for Calvin Coolidge. [Evil Republican]
Play Der Langrisser.