I like systems that are maintence free and easily replaceable. My experience so far in software engineering is that technologies die, so it should also be easy to replace the tecnology, like the hardware it runs on, the platform/os, the programming language and the framework.
https://web.archive.org/web/20031101212246/https://spacecraf...
Minimize negative(painful) notions as much as possible, ideally approaching zero, while maximizing positive (pleasurable) notions.