I kept XP until support for it ended.

When I bought a new laptop, W7 was still available as an alternative to W8, and I've been very pleased with it -- and was therefore surprised to learn it was derivative to Vista, the worst OS since Windows ME.

I asked Rory about W10 -- he said he liked it and it is stable, but he occasionally had difficulty finding things.

I'm thinking I'll wait for the the first maintenance release, then switch.