Is a beta version always better?
Beta version of a software is still under testing phase (being tested by a wider group of users/developers). It's definitely better than the alpha version (wherein testing is done by selected group of developers). At beta stage, the software still undergoes cycles of bug fixing.
Let's put it this way. If you want to see the latest features in a piece of software, then Beta is good. If you want a reliable, trusted and tested software solution, Beta is bad!
A beta version is better than an alpha version, but software released in beta is still in a testing stage, i.e. not fully developed. Check out this Wikipedia article on Software Release Life Cycle for a better understanding of the various terms and their meanings.
Beta version is the name ~ or in other words signals a stage in development.
You might get the best overview about it within the Wikipedia article
But to make it short a beta version could also be called preview:
It's a stage where mostly all planned features have been integrated, tested and the software is released to a broader audience to gather feedback on usability and system specific problems and bugs.
So a beta version can be better since it has new features and bugfixes but at the same time it might contain new problems which are not present in a previous release.