There are only three windows where the game is (generally) fun, and shines in the way it’s mostly meant to shine. The first is rank 20. The second is zero stars at rank 5. The third is low legend.
If you’re at any other rank, it’s just an supremely dull exercise of encountering one unimaginative midrange hunter deck after another (or something similar). Ranks are completely arbitrary, and don’t signify anything. You’ve accomplished absolutely nothing by reaching rank 15 compared with reaching rank 5, for example. It’s just a matter of how many hours you’re willing to play in a single month. The only meaningful rank to reach is legend, and anyone who goes out of their way to intentionally reach legend more than once for the cardback simply has way too much time on their hands. Or they’re a masochistic psychopath.