When comparing Haiku vs OS X Mavericks, the Slant community recommends Haiku for most people. In the question“What is the best desktop OS?” Haiku is ranked 29th while OS X Mavericks is ranked 47th.
Ranked in these QuestionsQuestion Ranking
Pro Very Fast
Pro Beta has been released
After about 6 years since the alpha version, beta has been released on Fri, 2018-09-28. Check here for release notes.
Pro Only need 512mb ram
Pro Battery optimization
There are many features that improve battery life, such as App Nap.
Pro Great if you don't like El Capitan and up.
Relatively fast and retains many design decisions of the OS X of old.
Pro Memory compression features
You can have a lot of things running yet have plenty of memory left.
Pro Free if you have Snow leopard or Lion
Pro Very tweakable
There are many things you can still change through the terminal.
Pro Still supported so far
Con No one uses it
It's a very niche OS that no one uses.
Con Small community
It is important when developing to be familiar with tools that other developers use. You can make any utility in any language you feel like, but if it's in an esoteric language that no one can read targeting a small platform that no one uses, then it was just something you did as a hobbyist, not as a developer.
This is not to say that Haiku isn't a great operating system to hack around on. Just don't delude yourself into thinking you're doing it to get familiar with tools that you need to know to be a better developer.
It's still in beta and quite unstable. Making it unsuitable for developing applications of any kind.
Con Outdated OS version
No longer supported by Apple (neither bugfixes or security fixes). The last release was in 2014.
Con Slower compared to previous versions
Con Very hard to find
Apple is very keen to only show the latest version.