It depends on your personal choice as both are good . M.Sc Biochemistry deals with the study of life of plants and animals . It has different parts :

Animal biochemistry , Plant biochemistry , Medical Biochemistry , Clinical Biochemistry . It has good scope in teaching field in medical and dental colleges and there is a lot of scope in abroad also . By doing M.Sc Chemistry the future scope is also good . You can become a teacher and also a research scientist in ISRO , DRDO . The course you take depends on your liking and interest and your skills as both are equally good .

Hope this helps you.