Lots of players consider the post-2012 basses from Fender to be excellent.
But if you want "vintage" there are lots of dates that have varying degrees of significance, as noted by several posters above. Some are more significant than others, because they deal with actual changes in the way the bass was designed, rather than changes in company ownership or who was hired when. For example, there are years when pickups were changed, neck profiles were changed, body woods changed, fret wire changed, etc. Some of these changes can make a real difference in the way the bass feels and sounds. I'm not aware of a definitive time line that tracks these changes... that would be a good project for some TBer who has more knowledge and time than I do (or maybe it already exists and I just haven't stumbled on it).
Bottom line is that if there's a particular style you want (for example, you are looking for a fat neck, small fret wire, rosewood board and through-body stringing) you should figure out which years of production to look at, and go from there. But your best bet in all cases is to try before you buy if at all possible... you'll have a happier life with fewer disappointments.
But if you want "vintage" there are lots of dates that have varying degrees of significance, as noted by several posters above. Some are more significant than others, because they deal with actual changes in the way the bass was designed, rather than changes in company ownership or who was hired when. For example, there are years when pickups were changed, neck profiles were changed, body woods changed, fret wire changed, etc. Some of these changes can make a real difference in the way the bass feels and sounds. I'm not aware of a definitive time line that tracks these changes... that would be a good project for some TBer who has more knowledge and time than I do (or maybe it already exists and I just haven't stumbled on it).
Bottom line is that if there's a particular style you want (for example, you are looking for a fat neck, small fret wire, rosewood board and through-body stringing) you should figure out which years of production to look at, and go from there. But your best bet in all cases is to try before you buy if at all possible... you'll have a happier life with fewer disappointments.