It's ranked may be 250+ in world rankings. The professor is not a star but has few publications. Has at least one publication in a year...some in IEEE some in other journals.

I want to go to academia because working for companies and fixing their immediate shits doesn't make sense to me. I can't do what should be done. Have to always serve the boss. I want to be in a place where I learn and whatever I publish be of some value. Not just another software or another web application.

I think 10 years after. After 10 years , I don't want to be some manager/lead of some X company working under some boss. I want to be an expert in some field, distinguished and want to have my own identity not just X number of experience is some company.

I want to do research, valuable work.

That's a very good goal. You clearly need a better managers and better companies to work for. The research experience of the PhD might help, but it's not the solution to all problems.

For a more pragmatic point of view, look at where your future professor's students are. In a 250+ ranked school, the school name is not going to land you a great job by default. You'll need to be working with a good professor. Your summary of the publications of who you are working with doesn't seem stellar, but without details on where he publishes I can't say much. How many students does he have?

Do you have only that one offer or more?

He has 5 students of which 3 have completed PhD, 1 is in progress and another one is MS by Research.

This is the only offer I have.

My advice is to chat with previous and current students to get a feeling on how it is to work with that professor. In this way, you get a view of their experience.

Is the PhD in the US, Europe, or somewhere else?

As for government funded: you also get a monthly stipend, right? How long is the PhD in your country?

Not sure about the stipend. The PhD is typically 4 years.

Why not go for a part-time Phd and continue working. Might be a hassle for 5 years but you get the financial security for your family and follow your dream.

Also, it's a paid position, right? Never go if it is not payed, it's not worth it.

It doesn't pay me but I don't have to pay either except some admin fees. It's government funded.

If it's government funded they should provide you a PhD grant. If not, you should be careful before going into that PhD.

I second that. A CS PhD without student funding (at least a few 10K $ a year) is suspect.

Hmmm... I'll ask the professor !!!