I only skimmed over this thread, but I agree with the people who mentioned 'A Farewell to Arms' as the best Hemingway book. Personally I think it's the greatest book written in the 20th century. It's use of symbolism is efficient and more subtle than 'For Whom the Bell Tolls', and the war scenes and dialogue are far less repetitive. In addition, there are also elements of social criticism (though not on the scale of 'The Sun Also Rises') and a great offering of what war truly is. No other writer has ever so truly and simply evoked emotion in written form about armed conflict.
If you don't want a "war" book, then yes, 'The Sun Also Rises' is his next best work. 'A Moveable Feast' may be fun to read, but it is not on the same level of literary achievement. It's a beautiful nonfiction portrayal of a key time in the life of one of America's greatest writers.
For number three, I think you are looking at 'Old Man and the Sea', just by pure originality and influential prose. After that I'd say 'For Whom the Bell Tolls'. Those two, SAR, and FTA, are all genius and American literary masterpieces. Other works such as 'Death in the Afternoon', Moveable Feast, 'To Have and Have Not', and 'Men Without Women' are good, but clearly not on the same level.
If you are looking for the best Hemingway writing in general, check out the short story collection "In Our Time". It was the first thing he published, when he was 26, absolutely beautiful writing. The book is short and easy to read. Read it twice and you will get much more from it. The final two stories in the collection (Big Two Hearted River I and II) are my favorite of all time.