It seems that I have missed out on the grand decade of baseball card collecting in the 70s. The 70s is my second favorite collecting decade after the 90s. The reasons for me to like the 90s and the 70s differs.
My love for the cards of the 70s is that the Topps base set was king. Every card collector of the 70s was ripping packs of the same product. Each set of that decade was different. Topps changed it up in a good way by mixing great photography and random color schemes. The mustaches, afros and other 70s hairstyles worn by the players also makes the sets stand out.
The reason that I think the 90s is the best collecting decade is almost the complete opposite reason why I love the 70s. The 90s had great variety. The several card companies that came up with the sets churned out tons of product. Every kid had a choice of several sets to find there collecting niche.
The 90s was similar. Just look at some of the cards released by Fleer or Skybox. Fleer just though a bunch of colors and graphic onto cardboard and called it an insert. I dug that.