Definitely back. It has to be the design but some comfort too..

I have lived in two places with breakfast bars in American style kitchens. I found that I tended to spend a great deal of time sitting there so a bar stool with a comfortable back is important. I made mine from pine, copied from some I saw in a bar. I was also given an old captains swivel seat from a yacht so I built a stand for it, reupholstered it and unfortunately left it for the new tenant who liked it. That was one of my favourite seats, to sit in comfort at a breakfast bar rather than balancing without a back to lean on.

A back would always be a preference for us. Backless stools bring back memories of high school chemistry lessons. And personally, I'd do anything to avoid that...

Yes definitely with a back, if you are sitting for any length of time this support is a must.

I like a bot of a back - just not so high that it dominates the breakfast bar island. And good padding!

Caldicot Kitchens

Definitely a stool with a back & preferably a swivel too - easier to get on to !!

Yes, definitely with a back. I agree with what everyone else here has said but you are all missing the most important reason...not as much chance of falling off after that second bottle of vino!