If you know how many competitions you'll be entering (usually 3 bottles per comp), and how many bottles you may wish to gift to friends, then I'd bottle from the carboy first and then put the rest in the keg. In my case, I use a plastic bucket (w/ spigot, same thing as a "bottling bucket") as my primary fermentor. It makes it really easy to transfer into bottles or keg via the spigot (no siphon needed).
Otherwise, I'd put the bright beer in the keg and if there's any left over (there usually is) in the carboy or fermentor bucket, I'd bottle the rest. This is my usual method since I don't want to chance getting slurry into the keg. A little slurry in the last bottle is no big deal.