i'm personally indifferent about cards i see, but if you're looking for stuff that'll bring in the most credits for you, i recommend anything for the chaos dragon and blue eyes dragon builds, the new ghostricks, and your general staples like Black Luster Soldier Envoy and Ally of Justice Catastor. i'm a judge so i spend most of my time and effort just piecing together functional decks for teaching at various skill levels, only 2 or 3 of my 15+ decks at any given time are tournament competitive. Also i have a set of Balmungs already, was just pointing out that those two decks were the only ones that have a lot of setup for a level 4 synchro, using it elsewhere and you're sacrificing deck viability for level 1 and 3's.