It's much harder for a short person to reach the floor to scoot a chair out than to simple swivel and then slide out.
The kids cannot push a stool back. Get the swivel ones.
Be aware though.
Bar stools are about 30"
Counter stools are between 24" and 26"
Measure and find the ones that fit your island best. If it's the same height as your kitchen counters then you can't get bar stools, they'll be almost the same height as the island top.
I have a breakfast bar that's counter height. I have an island that is 1" higher than my counters. So I bought one stool 24" and one stool 26". The 6 year old sits on the taller stool and the 9 year old sits on the 24" one. This fits for them right now but once the 6 year old has a growth spurt and gets taller he's not going to be comfortable on the 26" stool. The 2 year old sat on the 26" stool this weekend and he did just fine. He can also do well with a regular bar stool too but his knees were barely under the edge of the island.