In what has to be a set so poorly done, that it's awesome, today we get some 1990-91 Pro Set cards. I have a complete set, but not a master set - there are so many errors in this set, corrected and not, that I don't really plan on getting a master base set, but you never know.
We do gets some additional Leaf keepers here though.
One of the other parts of this set people think of or remember - the ref subset and the fact that, at 700+ cards, you get those, a coach subset, hall of famer and all star team subsets too. If you allow for a big set, plenty of good subsets you can include. Nowadays, the base set is 200 cards and all of those subsets are insert sets with 5 different parallel versions.
There is something to be said for the simplicity of a big base set.