Every time a set with Krenko is released, we see a small spike in the cards price as Magic players the world over are suddenly reminded oh yeah, this is the best possible goblin card ever created. Its not going to pay for your pack, but you can probably convince someone to trade for it
This is the most redundant group by a long way and as such you can build almost entirely to "Reanimate" without dipping into other themes
If we were to judge cards in this ranking by their power/budget ratio, Skullclamp would most likely be #1
Doubling Season Doubling Season from Ravnica: City of Guilds hasn't made much of a splash in 60-card formats, but it goes in many different Commander decks of all varities, because it straight-up doubles things players care about, like loyalty counters on Planeswalkers, for example
Arborea Pegasus Blink targets always have some kind of a home, and Arborea Pegasus has a sorta okayish ETB
Moreover, it was known to be one of the best decks