Open source, of course. The leverage you get from being able to use all those brains and eyeballs in addition to your own is colossal. It's a competitive advantage traditional operating systems vendors are finding they can no longer ignore. Instead, it's cheerfully absorbing its competition. These are all things the worldwide community of open source hackers are really good at supplying.
Customers get better software.
By joining the Linux community, everbody wins. Each was punched for insertion into a three-ring binder and could be obtained for a nominal fee. Applications included small langauge interpreters for 8080, Z80, and 6800 computers, games, etc. I have a couple of old computers from that era and wonder what remnants of those documents still exist. I'd be thrilled to obtain photocopies or read them on the website.