Even when we travel, we use water bowls. I love the bowls that twist onto a clamp. They are just high enough that bunnies won't dig in them and they can't pee in them. They are perfect!
The photo below shows our rabbits' set-up in a hotel room. If you look carefully, you can see the water bowl attached to the x-pen.
Bowls for sure. Unless there's so odd scenario like your rabbit making a really big mess or peeing in the water, which in that case you have other problems to deal with first. They don't have to be stretching their necks out, and for my bunny she drinks more water with the bowl, which is pretty great. And can you imagine how treacherous it must be to drink from a bottle only one drop at a time?