IMHO the best electric shaver for arms is the Braun Activator. The Activator is soon to be replaced by the 360 Complete. It has an improved cutter and foil design. The 360 replacement cutter and foil will fit on the old Activator.
If you want to spend less money, go with a Remington foil. They shave close but the foils don’t last as long. An MS-370 can be purchased for $30-40.
RJC2001