Another vote for the car.
Not sure how old your children are though.
Our thought is we have young kids. Yes maybe you don't have to wait 40 minutes every time but seldom do you ever walk out of your room and there is the bus to the park you want waiting for you. You have to wait somewhat.
With young kids I don't want to find myself in the boat of just missing a bus and having to wait 5,10,20,etc mins for another with a tired cranky child. Would rather be able to jump in my car and go without standing around. Then again my wife tells me it is ME that can't stand and wait for the bus.
Also find that at night when we leave the park kids are asleep in the stroller. We have had pretty good success transfering them into ther car seat and then to the room keeping them somewhat asleep. Don't see that happening if they had to sit on the bus. Now I would have a tired cranky kid at 12 am. Then again you might not stay as late as we do. We generally close the park.
Another plus is if you want to go from resort to resort. We generally have at least 1 meal at another resort. If you take the bus the only way is to take a bus from your resort to a park, then change and take bus from that park to the new resort.
It really is a personal preference. I just know myself and my kids and there is no way I/we could wait for a bus. Others think it is great. I am sure at some point when the kids get older I'll try it at least once. I keep telling my wife every trip we should try it one day just to see, but can't get myself to actually do it.
We have also had good luck with car prices. Generally low to mid $200's. If that ever changed maybe that would change my decision.
Good luck
One more thought. Have stayed numerous times at CBR and you do not have an assigned parkng section. It does make it A LOT easier to go from your building to main building if you are not in preferred section.