I went for Luke: ROTJ, but ideally......I thought this would have been cool without the control box. It would get in the way of spinning and doing anything fancy.
Funny you should mention a Luke RotJ without control box, because that's exactly what my unfinished one is right now, and at this stage of completion I thought to myself, "You know, this saber would've been so much easier for Luke to duel with if he didn't have that control box on there..." :P
That said, I vote for the Luke RotJ as my favorite OT lightsaber, as it was the first lightsaber I ever held (in toy form, at least) and started my lightsaber collecting passion. I'm amazed at how things like that stick with you...
That said, my favorite OT saber from a design point is Obi-Wan's lightsaber. Just the amazing amount of items that went into it, and the variety... Sink knob, machine gun booster, camera flash clamp, calculator bubbles, transistors, rifle grenade, balance pipe from the flame tube of a jet engine... I mean, it takes some serious ingenuity to take so many disparate parts like those and put them together into a really great lightsaber.
Still, my absolute favorite is Luke's RotJ (the V1, but the version with uneven grips. No idealized MR replica for me!);D