My favorite is probably running Naya colors (GWR)
I have two separate Commander decks dedicated to it xD piloted by these two. For those not familiar with that format, you have one card that's a legendary creature and then you build a 99 card deck that supports it. (But they have to share the exact color identity of the commander card.)
My all time favorite card is this one. It's a simple card but I love it so much.