Depends what you mean by "best deal". Going that far I would want to minimise the time travelling (even in Business) and that means BA, Qantas, Singapore, Malaysian, Thai and Cathay. Airlines based in the Middle East add at least one more stop (at their home base). If you think the dogleg via Hong Kong (Cathay) is too long then Korean and Japan Airlines won't appeal. United via the US means having to deal with US immigration (they don't do TWOV) plus the TSA and their service suck and their financial situation means they keep pulling in their horns. Air Canada might work, don't know what the connections are like.
Try the airlines direct then Opodo, Expedia and the like then buy a copy of the Sunday Times and peruse their travel section and hit the phones to people like Trailfinders.