Master. Transfer. The first depends on the condition. The second takes pure time and money.
Nothing comes to mind as first rate "old" BDs. Hmmm. I think 2001 is supposed to be decent. Not reference PQ or anything, but quite an improvement.
The best transfers I've seen of "older" (not Vertigo old) are actually on HD-DVD. The two best I think of are The Thing and Darkman. Darkman has some of the most detailed faces Ive ever seen on either format. The color stock is representative of its time period; not as wide of a color palette. The Thing shows the master's age once in a while, but man, unbelievable man, unbelievable.
The Last Starfighter is a step down for sure.
Peter Jackson's The Frighteners is close to bottom of the barrel. Still a very fun movie, but PQ is a no go.
Ah yes, I have Life of Brian on Bluray. Its alright. Its ok. I also have Blazing Saddles, but waiting on a couple of friends before throwing that on.
Whether older, or current, the quality of master is often associated with the budget of the movie itself, AFAIK.
Here is one thread I use to get some help in PQ purchases for BD:
You can also somewhat predict the PQ by the amount of gb's taken up on the 25g or 50g BD. Or the video bitrate. Bitrate is very variabe, a certain movie can have 5x the bitrate from one scene to another.
Bitrate specs, total, video, audio:
Hope that gets you started.
If you want pristine transfers of older movies, Criterion is releasing their first 5 in November. I already have all 5 on preorder. Also, Godfather will be here in a week and a half, and is supposed to have gone thru a pristine transfer. If I understood correctly, even the DVD was using the same master as the VHS?
I really dont know much about this stuff I suppose. hope this helps.