Eh, they’re about equally disruptive in the ways that matter, maybe slightly less so for Tomorrowland, actually. Taking Space Mountain offline will be equivalent to knocking out Big Thunder, but Space does have the benefit of neighbor TRON covering a similar ride type. The Speedway will probably be about as visually disruptive to redo as the Rivers, but I’m also imagining that, depending on what they build, the timeline might be shorter as a result of less land prep. The other things the land needs (new PeopleMover sets, Stitch replacement, Laugh Floor replacement, etc.) are just reworking content in existing theaters or along existing ride paths. The bones of the land are still good, and most exterior updates could easily be handled piecemeal, like the recent replacement of the Cool Ship.