I can attest to The Clone Wars getting very good as it goes on. I think the airing wasn't intentionally out of order, but rather that as the showrunners got more used to what they were doing, they were able to go back and have side stories that took place before, or show character backgrounds interspersed, etc.
Most importantly I think the show does a good job of showing us the authoritarian streak Anakin's developing alongside his increasing belief in unilateral heroics over negotiating and discussion, so his hamfisted fall in Ep III makes a bit more sense. But the side characters are given a lot of fleshing out, and we finally get an explanation about whether the Clones had autonomy or not in regards to O-66, which is huge. You also get a real sense of why some people really did have legitimate grievances with the Republic such that they joined the CIS, and also how the CIS' leadership exploited those grievances for their own ends.
The relation of some of the ex-CIS sorts to the Alliance gets a bit of a look in between TCW and Rebels (and honestly, the comics have been pretty fantastic too). Notably, in the trailer the character played by Forest Whitaker was in TCW - he led the resistance to a CIS takeover of Onderon - only for the Empire to rise, and so presumably some of those Onderonians went back into opposition.