What are the top CI/CD Solutions?

I’ve searched this Kalutra forum and couldn’t find a clear answer. Does anyone successfully use continuous deployment tools?

Selecting the right Continuous Deployment tool depends on having an understanding of the diversity of tools and whether the features offered by a tool are the right fit for your dev and deployment processes. Can anyone please share your experience?

How long does it usually take for one to build full-blown ci and cd tools (from scratch)?