When comparing Solus vs Haiku, the Slant community recommends Solus for most people. In the question“What is the best desktop OS?” Solus is ranked 15th while Haiku is ranked 18th.
Ranked in these QuestionsQuestion Ranking
Pro Rolling release
Pro Modern desktop environment
The default desktop environment used by Solus is called Budgie and is quite nice and minimalistic.
Pro Easy installation
The installation procedure for this distribution is quite simple. It's GUI based and all you have to do is to follow the instructions given by the installation window itself.
Pro Exclusively for desktop systems
Pro Great package management
The software center makes it really easy to install the latest software through Snappy and Flatpak. Including third party software.
System boots quickly and stays responsive. Does what operating system should do, and does it really well.
The system itself is very stable. All packages in the repository seem to be carefully picked, well prepared and run stable.
Pro Seamless Packages
It may not have the most obscure packages, but the packages it does have is a good number of everything a Linux user needs. Gamers, developers, desktop users, etc. all have the necessary packages and then some. The packages themselves are integrated perfectly and are very well updated.
Pro Most stable Rolling Release Distro
Pro Built from scratch
Con Slow development
Con Software a bit slower to launch than for other distributions
Con Forums are not very friendly
Con Not much software
There is not much software available.
Con There is often a black screen after update
Con An upgrade breaks the system quite often
Con The default desktop environment is not very customizable
Maybe because it's a relatively new project still in its infancy and this may be fixed in the future, but Budgie is not very customizable. You can only change the theme and wallpaper.
Con No USB Image writer
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.