Viridian makes a good point about the condition of the master tape. Even if stored immaculately it will have degraded over years and decades.
I go for the original, pressed in the country in which the recording was made. There is a feedback process called the 'test pressing', that occurs between the artist and the record label. It only seems to occur in the country of origin. Working duplicate tapes of the master are generally shipped overseas for release in other countries. So the country of origin will usually have the sound that the artist approved (not saying in all cases that that is the best sound, but simply the one approved).
In this age of digital and limited LP releases, there are less differences between the countries if they are all working from the same digital master.
One thing that was a problem for some releases in the 60s was the issue of mono. There was a product designed so that the record labels could produce a single stereo LP that would also play properly in mono; this was so they did not have to do both mono and stereo releases. This product (Haeco CGS) was a processor that messed with phase, which muddies center channel information.
So if the reissue lacks that processing, it may well be that the reissue can sound quite a lot better.
Acoustic Sounds has done quite a lot of work with their pressing machines which are considerably more still during the pressing process. This makes for quieter vinyl. We have been cutting LPs, some of them reissues, where it appears that we are able to turn out masters better than the original. We are using a modified form of our M-60 amplifier for the cutting operation. IOW there are still advances being made in the LP process. If, during the mastering process, you have a good master tape and the original LP in front of you, I would say that there is opportunity to have reissues that can sound better than the original. You just have to listen and see :)
