Science

Both Courses are good and equal according to future prospects it's depends upon your interest that what you want to study. I will give you little information about these courses, which will help you to decide what to choose:
B.Sc Horticulture program is all about cultivation of plants, starting from seed related study to scientific study of cultivation, genetics of plants, plant diseases etc. In short, it is all about the application of scientific knowledge in plant cultivation and thus increase productivity and yield.
B.Sc. Microbiology program is a broad discipline that involves the study of the biology of bacteria, viruses, protozoa and fungi. The main focus of our course is the pathogenic potential of the organisms that cause disease in man. Microbiologists are needed to do the research required for the future battle against diseases worldwide and to exploit microbes in the production of food.
So, these are the primary information hope which can help you to decide. Choose your field with your keen interests. Both are good career options.
Good Luck.