Yes, this is the label that sets the standard for how re-issues SHOULD be done. If there's an artist or genre that you like AND it's available on Ace, then you should get it there.
How did they end up getting/doing some Fantasy material?
I recently got the great two discs by Percy Mayfield, one from Fantasy, the other from Ace - seems in that case they're identical (except for course for the logo and some minor differences in layout). In others, they made their own Fantasy twofers. Was that one of those licensing deals, just like ZYX had in Germany?