Sir mere 12th me 77% bane he mujhe aage konsha sub. lena chahiye

Dear aspirant,
Medical is probably the toughest and the best course our there. With an aging population by 2040 the world will be needing a huge amount of Medical professional. Especially countries like China Japan Korean will have a lot of scope in the medical field. Even low paying jobs of nurses will soon become high paying.
Incase u are into physics and bio I'd say bio tech is probably the best bet.
Now let's look at engineering, electronics sector in the next decade will start to boom as the doping techniques advance the ability to create faster core will increase exponentially. Just look that development in the smartphone market over the last decade we went for button to gesture control!
Also you have Field like Comps and it that will always be in demand also data science is going to be indemand soon.

Now for non science field commerce - CS CA will as usual be very hard by worth it

I'll be honest I have no idea about arts. But the role of psychologist will be indemand soon.

Rank
#1 medical , difficulty -10/10 but job guaranteed
#2 engineering, difficulty -6-10 depends on college and grades
#3 commerce , difficult if you decide to pursue CA or CS
#4 Arts difficult if you pursue foreign studies in language
Note: in science field you'll have no time to chillax especially medical with 10 years of study.