Remember when buybacks were rare?
Take for instance, this – Canseco’s most famous Topps card, ever. In 2004, Topps gave collectors Jose’s first ever buyback auto, and hand numbered it to 99. (Super rare, considering the they probably produced millions of them.  The 1991 Donruss Elite is numbered to 10,000, so this buyback is less than 1% of those!)
In 2015, they upped the ante and released one numbered to /14.
In 2016, they released it again, but numbered to /97. The only real on card difference being the stamp is on the other side. Oh, and several non auto versions stamped with “65th” in black, red, blue, silver, and gold.
In 2017, they released it again, this time with no autograph, but stamped in various “Rediscover Topps” colors: bronze, silver, gold, blue, and red.
In 2018, they did a “limited” run of buyback autos of it, numbering it to /10.
In 2019, they released it again, numbering it to /57
In 2020, they released it again, numbering it to /63.
Regardless of how many they create, a signed rookie cup buyback card of Canseco is ridiculously cool. If you have a 2015, 2016, 2017, 2018, 2019, or 2020 RC cup buyback auto, be proud. I wish they would stop producing them, but they won’t, because they are in business to make money. It is a testament to how iconic the card is.
It is important to note that in spite of how many new buybacks are pushed out, it should never take away from the specialness of the originals.   
As for me, if I had to pick my favorite, I’d pick the only hand numbered version…the original: 2004.