They are two of my favorite sets of all time, def tops 5 for me.
That said, 56 is my choice. There are 340 cards and 34 are hall of famers. Easy math says that is 1 out of every10! It is also a set without high numbers and short prints.
53 is beautiful but can get pricey with the high numbers. It also missing a lot of the stars that had exclusive contracts with bowman.
Happy collecting and welcome to the other side!
ps. If your wife likes 56 its a no brainer. Might get her into the older stuff and if she is like my wife she will encourage me to spend a little more if she is involved
