Vishay makes a lot of different resistor types ranging from cheap generic resistors to expensive Z-foils (they may have even more expensive ones that I'm not familiar with).
I have used Z-foils (both Vishay and Charcroft which sound very similar to me) as well as Audio Note non-magnetic Tantalums (mostly the silver version). These are excellent resistors with a clear (to me) advantage in SQ over more generic offerings. I think the Z-foils are a bit more transparent and the Tantalums are a bit richer sounding.
The AN Tantalums are available in a wider range of values and higher power ratings, so I've generally used these in my tube projects.