Hello buddy, it's depends on your interest. If you want to change your field from engineering to management than you should go for MBA exams that are CAT, XAT, CMAT, IIFT, SNAP for different MBA institutions. But if you want to do MBA from IIM than you should give CAT exam. 

Otherwise, if you want to stick with your engineering field than you should go for Mtech for which you have to clear GATE exam. 

Best of luck for your future buddy.