N1 I've run 3 times over the years for different groups - different result every time - i love it as a ref and its now done AD&D, 2nd Ed & 3,5 without any real conversion hassle
U1-3 (Sinister secret of salmarsh, plus the follow ups) are also nice - I like the fact the first book is split into a couple of smaller sections to give your low level characters a chance to recover / level up / think about the plot. And it does have a nice plot with some genuine twists (that can also be ignored if you just want to hit stuff)
B2 (Keep on the borderlands) was the first adventure i ever bought - its basic, but none the worse for that