There is no single best course after 12th, because the best course is the one that matches your interests, strengths and career goals, not the one that is most popular or that others tell you to pick. A course that is perfect for one student can be completely wrong for another.
Start from your stream and interests. Science students can explore engineering, medicine, research, architecture, IT or pure sciences. Commerce students have options like CA, B.Com, BBA, economics and finance. Arts and humanities students can pursue law, design, psychology, journalism and civil services. Within every stream there are many strong paths.
Look at where careers are heading. Fields like technology, data, healthcare, design and digital skills are growing fast. Choosing a course with good future demand that also genuinely interests you gives you both opportunity and motivation.
Consider course details, not just the name. Check the syllabus, the skills you will gain, the job roles it leads to and the reputation of colleges offering it. Two courses with similar names can lead to very different careers.
Example: A commerce student in Vadodara assumed B.Com was his only option, but after researching he found a BBA in business analytics matched his interest in data and business far better, a course he did not even know existed before exploring properly.
Do not pick purely on trends or peer choices. A popular course you dislike is harder to complete and build a career in than a less flashy one you enjoy and excel at. Keep some flexibility, since many degrees open multiple career doors.
One practical tip: For any course you are considering, find and talk to someone currently studying it or working in that field. Their honest day-to-day account will tell you more about whether it suits you than any brochure or ranking list.