Ok I own both a B King and Hayabusa. I love them both and to say one is superior to the other is silly. While north American haven't bought B Kings they are great Bikes. The Busa is great as well.
Strengths
The B King is IMHO far superior in traffic and is much easier to handle in the city than the Busa ever thought of being. Brakes are great and seating position is amazingly comfortable. Perceived acceleration is AMAZING, and here in North America you will not find 4 others like yours in every paking lot.
Areas of the B King that is not so Good , It is IMHO the Ugliest Production Motorcycle EVER Built and the Best view of it is over the handle bars where where Pivoting your right hand pretties it up real fast. The worst feature of the B King in my opinion is it's relatively small fuel capacity. Also it has been noted that the pillion is rather like riding on the business end of Dull axe, and at arrest me speeds the wind is very noticeable. This is not a bike to ride because you are cool and want to be seen on a cool bike, and "what is that is that?" is a question you are going to hear.
The Busa is great I personally believe that they are great looking (but Hey I like the Duc 999) Wind protection is great, the aftermarket is very very deep and you pretty much have to leave the planet not to find parts.( Just try getting a decent aftermarket Windscreen for a B King) Fuel capacity matches about the time you want to spend riding the bike. Oh Did I mention it redefined fast for motorcycles? The Pillion is by all reports far more comfortable than the B King
Down side to a Busa, the riding position is designed for someone 5'8 or less as proven by the number of products designed to improve it, at speeds below 40 it is awkward when compared to the B King, in traffic the riding position limits your view and you have to move around a good deal to be situationally aware. Just a Note in talking to some friends in Law Enforcement the note that the appearance and riding position of the Busa is far more likely to get it stopped than a Naked Bike at the same speed. Just something to be aware of.
My advice to the original poster is go find someone with a B King , ride one before you through you cash down. They are Both great bikes Neither is superior just different.