Of course 1984 is his best work, but i do think Homage to Catalonia is also brilliant,his Essays collection from Penguin is great too .
Homage to Catalonia is his best non-fiction book by far I think. I loved the way the Anarchists basically just took orders(although they never actually had to), because they knew they had to have some sort of structure to survive.
1984 for me is too depressing, I prefer Animal Farm for it's simplicity yet brilliance. Also well ahead of his time in being a socialist who could see the dangers in communism(something else he learnt while fighting in Spain).