For the OT, ask yourself this question: is what you’re looking for exactly what people saw in the theaters, projection prints with dirt/scratches/burn marks included, or are you looking for what a respectful Blu-ray release would have looked like, going back to original negatives and getting a high-res scan that actually shows a little more detail than would have been visible in the theatre, but still using all-original elements.
If it’s the latter, I’d recommend Harmy’s Despecialized for all three. SW 2.7 is the one I’d recommend, although it’s still far from perfect. I can see why people would prefer Silver Screen even if they’re looking for the respectful Blu-ray treatment, so it’s worth a look, but it’s not for me. For ROTJ, 2.5 is easily the best presentation IMO. ESB 2.0 is nearly as good as ROTJ 2.5, but not quite. A few warts that will hopefully be fixed soon in ESB 2.5. Yes, they technically include SE elements, but at this point it’s nearly impossible to find them unless you’re a much, much pickier fan than me.
There are lots of original audio options. Star Wars in 1977 had three different soundtracks (6-channel, stereo, and mono), which had different content (although the 6-channel and stereo were very, very similar). All of them are “original” (and I’m ignoring the fold-down options because that confuses matters even more). Lots of people here like mono best, because it’s what most theatres were equipped to play in 77. I prefer the 6-channel reconstruction because, again, it’s what a respectful Blu-ray release would have sounded like. Empire had three original mixes, the 35mm stereo, the 16mm mono, and the 70mm 6-channel. The 70mm version was a different video cut, and we don’t have a good preservation of that (there’s an 8mm digest which has bits of it, if you want your mind blown). The 6-channel option you get with Despecialized is essentially just a tasteful upmix of the original stereo mix. Jedi only had stereo and 6-channel, and again our 6-channel option is essentially a tasteful upmix or the original stereo, since we don’t have any references for the 6-channel (but we think it’s content-identical).
The 2006 bonus DVD were the theatrical video, as far as anyone’s able to say with certainty (there’s a few dubious quibbles). The main gripe is that they just suck, quality-wise. Also the audio isn’t theatrical at all, which is most relevant for Star Wars and Empire, since there are content differences between the mixes they used and the theatrical mixes (they used the 93 remixes for all three films).