Kaspersky and Bitdefender are very similar in terms of features and detection.
Their behavioural blocking (System Watcher and Advanced Threat Defence), as well as their heuristic scanning coefficient of detection would not differ too much either.
They are both light, with Bitdefender’s memory usage being a lot higher than Kaspersky and its definitions set being a lot larger. Kaspersky is overall more stable, however Bitdefender might be easier to use and with the Central platform you can take the hassle of AV-management in an Endpoint-protection sort of way. End of the day, it all comes down to what you’re used to.
Both of them offer secure browsers, if you are really into that.
I would not comment on Avast’s privacy issues, and I don’t believe that a product should be sent to the rubbish bin, just because once it was on the news. In terms of detection, performance and features set, it doesn’t stand lower than Kaspersky and Bitdefender. It lacks however, the Intrusion prevention techniques found in both other programs in question. Because you’ve mentioned sandbox, Avast is the only company of them 3 to offer it.