Hi Sabbia,
In my opinion I would go on the KK bus. We have done it a number of times and have always had a great time. I believe they were the orginal party bus and all the others have been trying to compete. I really don't know about the banana bus but others have told me they have done both and all agree the KK bus was the best. As for what night, I really can't say. I have done it on different nights and to me it really didn't matter, it was a blast. So whichever you choose I'm sure you will have a great time...