The squared off doors are what is known as 'World Doors'. Export Jeeps with hardtops also had square doors to go with the tops. In the US, all hard tops have rounded corners which makes it impossible to use a factory soft top door with a hard top. I don't know why they did this.
Back in the day Bestop made the Supertop line which is still being made which has rounded corners. They have the fold out window along with the sliders Joe pointed to.
Honestly, if I was going to run a hardtop, I'd get the full doors. It's a whole lot quieter and having roll up windows is a big plus. Sliding windows, while they look nice suck for daily use. You chould be able to get a pair of YJ doors for about the same price as those sliders.