I would find it much more natural to have both expand/collapse and upvote/downvote on the left, simply because text is left-aligned.
I find any functionality pushed all the way to the right side to be harder to use, simply because it's not "together" with everything else on the left. Your eye has to do more work to match right-side content to left-side across a whitespace.
I find any functionality pushed all the way to the right side to be harder to use, simply because it's not "together" with everything else on the left. Your eye has to do more work to match right-side content to left-side across a whitespace.