I need Arkham still, but have everything else on that list. Of all those, Orthanc is the weakest set. Thankfully, it is also the newest.
Tower Bridge is repetitive, but still a cool build. And the final display piece is great. As I said many times before, it is a MOC gold mine because of the pieces. This cannot be understated. The fact that it is about to go OOP means you should get it ASAP.
Death...err... I mean Best Star is my favorite set, bar none. Are their better builds out there? Yes. Are there better MOC friendly sets? Yes. Is there any set that combines a fun (yet pretty basic) build, tons of character, and a load of nostalgia at the same level? Not even close. Best Star is all about the experience and Star Wars love in it. It is a must buy for any Star Wars fan. All should witness the firepower of that fully armed and operational battle station.
Having said that, the only set IMHO that comes close to giving Best Star a run for its money is Haunted House. For what Best Star does for Star Wars love and nostalgia, Haunted House does it for old school horror film love and nostalgia. I would say Haunted House is the superior build of the two, but the sheer size and grandeur of Best Star still wins.
As for your list, this is how I would rank them personally:
Haunted House > VW Camper > R2-D2 > Tower Bridge > Orthanc. I still need Arkham to pass judgement.