I have been wondering about this for a while: what is your definition of "best cards for cube" in this series? It seems like power level is a major factor but not the only consideration, otherwise you could just call it the "most powerful cards in cube". Maybe a quick rundown of your criteria at the start of the video would be helpful. My favourite of the set is Cankerbloom. I always like a maindeckable disenchant effect and the aggressive body and counter synergies fit nicely into a lot of environments.
In many of my videos, I mention my criteria. In order to make the video the most appealing to the widest variety of cubers, I try to consider a more average cube. So I look at the MTGO Vintage Cube list and other popular similar cubes, to get a sense for that higher power level. I also look at peasant cube lists since those are popular as well. But every so often I'll include cards that I think are ideal at specific power levels and I will mention that power level when talking about the card. Often I will identify an existing card or kind of card that a new card could replace or complement. My personal cube is a bit more on the budget end (only a few cards are over $20), so I have to shift my mindset away from only cards I would personal like to run. I also make some videos specific to pauper cube, but I don't always do that for every set. I agree with Cankerbloom though! And it fits at every power level. Efficient enough for high power cubes, flexible enough for mid power cubes, and budget enough for low power cubes.
Yeah I think there's a few (pretty much only the rares) that stand on their own, but mnay of them were designed with the idea of being able to put additional counters on with other cards in the set. That said, I wasn't sold on any for cube specifically. Mercurial Spelldancer is pretty cool, but that's about it. Are there any you plan on adding to your cube?