My preference would be the clean, hierarchical view but there are a few filter-type scenarios where the order isn't known ahead of time or matter at all. For ex

My preference would be the clean, hierarchical view but there are a few filter-type scenarios where the order isn't known ahead of time or matter at all. For example a user might want to view a/b then append c/d (a/b/c/d) or vice versa (c/d/a/b). It is possible to make this with clean url but it seems like a bit more work since you might need more logic as far as parsing and routing. Edit: pretty cool how all the sibling comments are along the same lines :)