Which company would you suggest me to start my career in writing?

This depends on your qualification and your experience as well.

If you are a beginner then you can start with creating your identity through blogs, start as freelance writer, create content etc.

Also you can be specific about your writing interest like in fashion, food, travelling etc. Based on your interest you can apply in companies accordingly.

If you are interested in education and career then you can approach in educational firms as a content writer for their website content etc.

So first you decide what is your interest and accordingly proceed further.

Good Luck.