It is too early in the card collection season to declare a winner for best insert set of 2015 but the Gallery of Greats insert set from 2015 Topps Series 1 has to be an early frontrunner.
Gallery of Greats was a fairly tough get averaging 1 of these inserts in every 18 hobby packs or about 2 in every Jumbo box. The set goes 25 players deep and mixes current day stars with retired players. Only 6 current players are in the set, 7 if you count Jeter who just retired. For some reason 3 of the 6 current players are Dodgers and in my opinion only Kershaw belongs. Puig is too new of a player but with his hype I somewhat understand his inclusion. Hanley Ramirez is a complete mystery to me. I will show my bias here but I cannot see how Buster Posey isn't in this set and Hanley is. You can argue which retired players belong and which don't but it is harder to argue any of these players.
The design of these cards is great. The photos are bright, vibrant and shiny and really pop. The border area is raised, similar the the Gypsy Queen framed parallels but have a slicker, smoother feel. The decorations at the top and bottom are classy and the names, positions and insert set name are very easy to read.
Since I only cracked one Jumbo and a few packs, most of these were secured on the secondary market between eBay and Sportlots. I thought I would share nice big pictures of all 25 cards to show off the set. Enjoy: