I also agree with Syntax. Compared to the originals most reissue labels are a waste of time and money. Unless these originals are in the 'trophies for the rich' category.....
I make an exception for the blue note reissues by Music Matters (both the 33.3 rpm and 2x45 rpm editions). They are fundamentally different from RVG's original masterings (which were mostly cut very 'hot', delivering explosive dynamics), but they are very convincing nonetheless. The earlier Classic Records BN reissues sounded soft and bland by comparison. The Mercury Living Presence and RCA Living Stereo reissues by Classic were pretty good though, some even spectacular. The Ansermet Ballet Gala set and the Solti Venice are actually better than the originals (or at least my originals, which admittedly are not the earliest 1S lacquers). It's hard to explain the quality difference, as Classic supposedly had access to the original master tapes and Bernie Grundman behind the console in both cases. It's a complete mystery to me.
Another exception would be the Japanese Polygram reissues of the three Nick Drake LP's, originally on Island (and all three high priced trophies for collectors). They were part of a short lived series on 200 gram vinyl about 10 years ago. I don't know about the other titles in this series, but the Nick Drakes are really outstanding, better even than the UK pressed Fruit Tree edition from the late '70's that I have for comparison. They're out of print and probably collectable in their own right, but definitely worth hunting down.