Java or .Net - Which is Better for career?

Hi sir this is Navami Tiwari , I am working in a mechanical company with team of 5 members as fresher software developer in asp .net web api, linq, MySQL and entity framework from last 5 months, but I have spent my 3 years in learning java. I have a job offer in Java but they are saying that they will give training for 3 months so my salary would be less than my current salary. After appraisal at both the companies, my current come will provide me a little more salary. All game was of interest but I am confused now what is interest coding or Java vs .Net. I am not able to take decision for better career in future. One more thing what would be impact of working with mechanical company in its own ERP or to join a software development company to work in Java as a fresher. Please help me.
Any suggestion is appreciated , thanks in advance.