I built quite a few ARFs in the last 3 years, and i have to say it might depend on the model and size more than the manufacturer.
The quickest to build of my recent planes:
My Funtana .40, and my son's UltraStick .40: Both were started on a Friday evening after work, and were test flown the following Sunday aroun noon. ( And I do a lot of extra stuff not in the instructions).

The worst ARF I have built that took me weeks to complete: Lanier "sea bird' float plane; it should have been sold to me as a Kit, Not an ARF!!![>:][>:][>:]