Choice with company for GC

Hello All,
I am new here, so not sure I am asking in correct place. The question I have is.

There are two companies which want to sponsor me green card in one I am currently working already 3 years and other one which offered me green card and new job. So I am not sure what to do, the new company is smaller company and not that old, the one I am currently working is big company and pretty old.

Thanks for advice