-EPIV ANH Vader is an older model, takes 6AA batteries, and the handle is slightly oversized compared to the original.
-The Darth Vader EPV ESB is closer in scale to the original lightsaber prop handle, it holds 3AA batteries, and has an improved sound system. Overall it's better than the EPIV version.
-The Darth Maul single lightsaber (the cut in half version), takes 3AAA batteries, has an improved sound system I think, has brighter lights, and size-wise is pretty much spot-on the same size as the original prop. And should cost less than the double-blade package. I've been hearing that if you want a real good representation of a Sith lightsaber in FX form, the Darth Maul is the way to go, otherwise go for the EPV Vader.