Rebels for me. The Clone Wars never got me to care too much for the new characters it created early on. It felt like it was using my previously established love for old characters to try to get me invested, but it floundered for way too long, imo. Early seasons did feel like a sanitized presentation of the prequel trilogy for me.
Thankfully it got better. But I don't think I ever really felt like it was a must-watch, even to this day when I watch it just for the sake of catching up.
Were the bits of lore they set up fascinating? Yeah. But I feel like other mediums and storylines used those setups and lore in Clone Wars better than the show did. I think Son of Dathromir's story came off way more brutal and intense in comic form than it would have with the animation in Clone Wars.
Which is a shame, because I really loved Genndy Tartakovsky's Clone Wars miniseries.
As for Rebels, I think it hit the ground running. The fact that we were following one set of (brand-new) characters instead of flipping between different sets of people every three eps in The Clone Wars was an advantage.
They were able to bring in something new without too much expectation from my part while at the same time just giving enough callbacks and cameos/guest roles that were short and sweet. And yeah, I preferred the animation style too. I only hated exactly one character on the show(Ezra) and they were able to fix that in the course of the show.