Slowroll is experimental and it's still a rolling release that tracks tumbleweed. It might be less maintenance, but not necessarily more stable in terms of bugs. I've seen some people report pretty major issues with it in the last couple months.
Leap is the version you want if stability is your priority. You can even get the tumbleweed nvidia driver if you have an Nvidia card and want the latest driver. The only os I've used that was more stable than leap was debian. But Leap is much more flexible than Debian.