how was clone wars childish? it had parts that were darker than the movies, by far.
though to answer you question, I'd say Rebels plays it a bit safer being that its Disney now (clone wars was not disney when it aired, I think CN was more okay with more violence than Disney is)
But damn dude.. if you stopped watching Clone wars because you thought it was chilish.. well I hope you only say that because you didnt make it past season 2. seasons 1 and 2 where hit and miss, 1 for sure.. after season 2 is when it really goes full throttle. Highly recommend you give it another shot if you didnt get that far. If you did get that far and you still think its childish then .. well cant really help you.