Firecracker content is outstanding and more comprehensive than Zanki and Bros. The cards are pretty trash, though. Firecracker serves a different purpose than Zanki, which is to have the vast majority of the content that would possibly be tested on Step 1 outlined by section, + flashcards of this content. I personally think the pre-made anki decks are garbage, but I also understand that it's the best a lot of people have access to (other than making your own deck). I am happy to be making my own personal anki deck based on the Firecracker content (which is basically First Aid, Pathoma, and more, all in one), as well as the rarely missing stuff from Firecracker that is perhaps in First Aid and other sources.