No idea why I saw this today, but I decided to take a look...
I voted for EoB, and I was a massive fan of that. It was a really awesome game in it's time, and it had some really great moments, like flushing the toilets in the Dwarven levels
.
Unfortunately, I didn't see Battletech until too late, because that would have to take number 1. It was an extremely fun game, in which you could take so many paths, well, at least for that age it was non-linear. The only bad thing about it was the ending, which had a really strange code that I couldn't figure out... until the internet said otherwise.
For all who haven't played Battletech, I strongly urge you to.