I've ridden over 5K miles in India and Nepal. It'd be impossible for me to pick the best ride from that trip. The Spiti Valley, Ladakh it is all unreal. South India is pretty great as well, I can remember some spectacular rides in Karnataka.
Here in New York, I ride often in Harriman State park. There is great riding in the Hudson Valley and the Catskills as well. I've had some unforgettable rides up there and do my best to go as often as possible
People always say: riding in the city must suck, and for the most part they are right. However, when I read the OP's question I can't help but think about my Friday night rides after welding class this summer. 830PM sun setting, over the Brooklyn Bridge with a great view of the new WTC. Then up the FDR with the engine echoing off the side walls as the UN and Midtown come into view. I exit and take the outer roadway of the Queensbridge, look back down the East River, Rose Island and the sun has almost set. Through LIC then back to Brooklyn. It's only a 20-30 minute ride but every one of those rides were the perfect ride. No traffic, de-stressing, great scenery and a chance put my bike and myself to the test.
Sometimes the best rides are unexpected.