I'm not a frequent visitor but I always stay at the Oberoi. I care more what a hotel looks like on the inside than the outside. The Oberoi's room have a very warm, old-world feel them. I love the bar there as well - although it is more of a grand lounge. The Oberoi also has a great pizzeria - but perhaps that's a vote against it in the eyes of many ;-)

I've never heard of the Imperial but I'll check it out next time.