Android marshmallow = exceptionally bad.
BB10 is a fundamentally different OS (QNX based) than pre-BB10. but Pre-10 was also a good OS from a security perspective, just utter shit to develop meaningful third party apps for.
Windows...used to be horrible. Big changes around Vista (although, ~unusable). Since Windows 7, it's been "reasonable" in a highly managed corporate environment, and not bad even out of the box. 8, 8.1, and 10 have been improvements on that. It's actually easier to do a 10k user highly locked down Windows deployment (although expensive, and involving a lot of experts and third-party tools) than to do a 10k user locked down Mac OS X deployment. Apple had a lot of advantages by starting from UNIX and from basically starting after security was a "thing", but hasn't done as good a job on OS X security as I'd like. iOS, on the other hand, is amazing -- the only serious deficiencies I find with iOS are a lack of "enterprise as sole root of trust" (which no one does, with the possible exception of (Blackberry Pre-10 and post-10), or roll-your-own open source linux/bsd with a lot of trusted computing grafted on in ways which are not at all trivial to do), and a lack of emphasis on anti-forensics on the device itself -- if you unlock it, it contains an sqllite db with ~every message, which shouldn't be how they do it.
OTOH, on cloud services, Google is far and away superior to Apple. The biggest problem with Apple is you're largely pushed toward iCloud which is not amazing from a security perspective. The true win of ChromeOS was you were equally pushed to the Google ecosystem, which is amazing for cloud service security -- the sole problem being you're 100% exposed to Google, Inc. which is both a US company and a single third-party entity, but if you had to pick a single company to be responsible for your cloud services security, you'd probably pick Google on the merits.