Depends on what you're looking for:

Uncompromised fidelity, but low resolution: dark_jedi

Extreme but not perfect fidelity, mostly HD: Harmy's Despecialized

Grindhouse, scratches, hair and mouse droppings: Puggo

35mm restoration: You'll have to wait...

I personally prefer DJ for SW and ROTJ, and Harmy for ESB, but that's my taste. If you wait a few months Harmy will have a greatly improved SW that's likely to become my favorite. DJ's v3 DVDs are available now, the Blu Ray upscale is what's unreleased at the moment.