This list is my opinion only (of course). Now some caveats:
1. I did my best to list fantasy only and not sci-fi, but that line is a blurry one to say the least.
2. I only listed one book per series, and I listed the first book of the series.
3. There's a lot of great fantasy that I haven't read. There's also a lot of overrated crap out there. If your favorite book isn't on this list, I probably haven't read it. But, I may have just not liked it.
Hopefully this will give you some good ideas. Enjoy!