The general opinion is that bar stools with backs are more comfortable than the backless ones. It’s quite logical actually. Having something to rest against is definitely comfortable and even ergonomic, especially if you’re sitting on the stool for long periods of time. Backless stools can be comfortable too, usually if they’re only used periodically or for short periods of time.
Speaking of which, the Tolix stool known as a Tabouret can definitely add some charm to pretty much any bar or counter. It was originally designed for exterior use but its versatility allowed it to make its way inside the house.
You should also measure the space between the seat of the stool and the underside of the counter. A 9” to 12” space is a good choice. This means you and your guests would be able to sit comfortably without touching the counter with your knees. But measurements aren’t everything. You also need to think about the style of your counter-height bar stools, the materials they’re made of, their color and their number.
If not, usually you risk getting bar stools that are too high for your kitchen counter. For example, although these classic Tolix stools complement this island really well, they seem a bit too high for it. This means you’d be sacrificing comfort.