Hanging drywall on taller than 8-foot walls
Firstly, you may be able to source 54&quot; drywall. Two sheets oriented in the usual horizontal way will cover a wall height up to 108&quot; (9 ft) with one tape joint between them. The extra cost may be worth the effort savings.
If your framing is laid out accurately on 16&quot; or 24&quot; centers, 10' sheets would stand up (vertically) nicely. All tape joints would be vertical - none horizontal. The waste won't cost much.
Otherwise, it really comes down to where you want to work. The outcome will be the same regardless, since a well-done tape joint is more or less as strong as the sheet itself.
Normally you work top-down, so you'd have that joint near the floor. One benefit is that you have flat drywall where you'll install base trim instead of a tapered edge. The drawback is that you're taping a joint hunched over.
Pros will sometimes do narrow strips in the middle so they can tape both joints almost as a single joint, skimming it all out together. The drawback to that is that you're taping a flat (butt) joint, since one edge of the strip won't have a taper. That means a slightly thicker bulge in the wall. If it's done well it won't matter, though.