The biggest problem with this comparison is both series have completely different formulas.
Clone Wars is very much a series of three to four part stories that flesh out the setting during the time period between two films in the series. A core cast is present, but generally only one or two leads will show up as they bridge into the stories told in each arc. There is a huge variety of genres in the shows. Big battles raging for control over planets with heavy influences of war movies, Criminal investigations at the high political level, lighthearted episodes with comedic characters, thrillers that deal with military loyalty, rescue missions, villains trying to undermine each others power, even a kaiju film for crying out loud. While not every arc is great, there is a huge amount of stories and characters for fans to enjoy. The Continuity can sometimes be an issue with the less than linear production order, but it still is impressive that a cartoon has all of this.
Rebels follows a more traditional TV show approach. There is a tightly knit team of six to seven individuals who band together and have adventures along the way. They meet new allies and run from the bad guys with character development sprinkled in for the main cast. It is a much more formulaic, but structured show. There are no big arcs apart from season premiers and finales, but that is also a strength. While viewers may not have large awesome story arcs, they do not have to deal with a month's worth of dull episodes. If an episode was lackluster, come back next week where this character gets the spotlight.
It really is an apples to oranges scenario. I prefer clone wars as a structure more, as I prefer all of the stories told, but I can see why one would prefer rebels.