When was the last time BitBucket had an outage? Personally I don't see a lot of difference between the two platforms; or GitLab (my primary now). Github probably has the best UI, but Gitlab's has gotten a lot better; and there are always self hosted solutions like Gogs.
I've been doing on-going client work for someone using BitBucket and for weeks it feels like every other day has an outage related to their pipelines (CI) feature (the thing I happen to be working on).
It was constant banners about service disruption. There's a lot of UI outage related issues too, like the pipelines page starting to show a new build but never updating any of the progress until you reload the page -- which sounds like some type of API outage somewhere. I'm not sure if that gets reported as an outage but it makes using the platform not fun.
I'm pleased I don't have to deal with BitBucket any more, but back a year or two it felt like it had an outage that impacted work at least once every six months. Sure that might not sound like much, but it was always a pain.
Plus of course the service was so damn slow that using it was a daily pain.
There's a yellow banner (that you can't even close) shown every few weeks, and it's usually related to the Pipelines being down, again. That often results in degrading functionality in other parts of the project too. And it's still slow as molasses. I wish I'll never have to use Bitbucket again, in the future.
Yes, I use it for personal projects. I also use a company-hosted version at work. The built in CI is great. I can't think of a reason, other than price for companies, why to use GitHub over gitlab. Both are great, but gitlab's built-in CI I think is easier to use and better integrated.