What are the top 3 sectors where to start your business?

What are the top 3 sectors where you would like to start your business?
What are the margins there? (difference between cost of product and retail price)
Are these sectors resistant to changing environment (especially now during crisis)?
Where will these sectors evolve in the next 1-2 years?
How strong is the competition there?
Why these sectors?

Most important they say, as with any business is, location, location, location.

If you got the right goods but with a bad location, I don't think it will thrive.

At different times of economic development, money usually flows in certain sectors of economy.
At some times of our history it was oil sector, IT sector, real estate sectory...

Where do you think the money is flowing now?
What new niches are opening NOW where you can make big money tomorrow?

If you're speaking of information products online, these are the mega-niches.

1) Dating & Relationship
2) Money & Business
3) Health

First of all, Location must good. Start business in the field you know about.