Given that we don't know the number of active users of either service, I think it'd be difficult to draw any conclusions about their relative failure rates [based on horror stories.]

If we assume google counts Drive users the way they count Plus users, it probably has a stellar track record. :)

At the very least, there are stories about Google Account loss, which while perhaps not technically being "data loss stories", are in effect exactly the same thing.

I don't remember the details, but a friend got badly burnt a couple of years back with some "known problem" where switching from free to paid googleapps accounts made _everything_ disappear...