If fit and condition are about equal between frames, it is probably a wash. Which frame fits you best is probably more important than condition. Both are 7 speed, but I believe the 930 has 135mm rear dropouts. At least my 820 from the same era does. This will allow you to go to a 9 speed if you want. Unless you are going to convert to drop bars, I think that Hot Rod Lincoln's recommendation is probably a good way to go. I'd stick with mountain specific components: XT, LX or Deore. LX components are really reliable, and a tad less expensive than XT.
I've often thought about "upgrading" my 1993 820, but I can not force myself to do it. I just took it out of the original box last year and it is really "just like new". I'd probably get hit by lightning or something if I tried!