what is the best system optimization software for mac or a system cleaner
None. As for system cleaners, avoid them like the plague. They have a bad reputation for not removing everything that you want removed, but may remove stuff that you don't want removed.
Be careful with terms like
optimization. It has a very different meaning on the Mac than it does on Windows. On Windows, it means that files are defragmented and relocated for more efficient access. On the Mac, the term means that applications are prebound to their supporting frameworks in an effort to reduce launch times. In the case defragmentation, the Mac takes care of itself (with rare exception). Third party defragmentation software may degrade performance. In the case of optimal relocation of files, Apple explains that it uses a private bitmap to which the third-party utility developers are not privy. As a result, their software cannot increase performance and will also likely degrade performance.