What is the best CMS in building or designing website?

 Do the research and find the best CMS suits your need and requirement , There are many things to look for in a content management system but here are a few of the more important ones:

1. Quick and easy installation
2. Simple administration interface
3. Quick and easy extension of CMS for extra functionality
4. Simple template manipulation
5. Helpful user community

Drupal and Wordpress are widely used CMS's , and Magento for e-commerce. 

and Please avoid Joomla ( the worst CMS ever )

WordPress is widely used CMS, easy to use and understand.

Basm allah alrahman alrahim

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I like wordPress WooCommerce , for a bigger sites you can ask Profficinal developer to make it for you

The 3 are the best , but your website developer experience is The difference , for example if he know about the best plugins and widgets , or if he can make the Template with all built in plugins [ experience is The difference ]