Yeah, I'm probably in the minority on this, but I hated the way the Maul storyline was resolved in rebels. That felt like something that would have been more appropriate had A) Obiwan been more of a recurring character during Rebels or B) the death took place during the TCW). Maybe they could have held that off for S4 and instead thrown Maul into the mix with the whole Thrawn arc. From how S2 set things up, I was of the impression that Maul was going to be a constant foil for Ezra who was flirting with the darkside and was willing to use Maul to get a better understanding of the holycron as well as become more powerful. This would have been a great opportunity to flesh Maul out beyond what he has been throughout TCW and more into a villain who is a lot more patient, pragmatic and calculating about his lust for vengeance and power (which he ought to be after 14 years of isolation). I love the idea of Ezra trying to find ways to destroy the Sith as makes it all the more interesting to see how he will fail (given that episodes 4 - 6 are immutable) and what he will learn from that failure. The Maul/Ezra plot point represented an opportunity to go beyond the played out light side vs dark side dynamic of things and into something less predictable and more uncharted in terms of Star Wars storytelling.
Unfortunately, as Zenwolf alluded to, we go into S3 episode 1 and see the gains Ezra has acquired from flirting with the darkside. Then, afterwards and out of nowhere, this subplot is utterly abandoned and we see no trace of it whatsoever (even in the Maul episodes, which is a damn shame). Terrible writing. Absolutely terrible.
Kanan ultimately did die in S4, but by then, I had just about checked out of watching the show anyway so it was more of a too little too late resolution for me. I also liked Ahsoka impulsively deciding to not leave Anakin, by they screwed that up by having Ezra use "time magic" to save her as opposed to leaving her fate open ended, so that resolution was dull and uniteresting IMO.