What kind of paint should I choose to start painting?
It depends on what you would like/enjoy to get involved in. A lot is based on opinion where to start. As a child, I started with watercolor. For some artists, they say that watercolor is more difficult because of how fluid it is, and how it spreads compared to other paints. Making it more difficult to control for a first-timer. 

Acrylic could be a good start, because it is easy to dry, and you can get more done with acrylic paint, over a short amount of time. Compared to oil paint, that will take a longer time to dry. I have found with oil paint, it is beautiful ability to blend colors, compared to acrylic or watercolor. Oil paint can be very messy for a beginner paint.

It really depends on what you would enjoy. I found enjoyment in all three paints, but each one is kind of their own kind of technique and ability. 

From personal preference only have found mine to be from easiest.  

1)Watercolor.
Pros: fluid colors, dries fast.
Cons: Could spread to other colors and ripping paper from getting damp.  

2)Acrylic. 
Pros: Fast drying, can make layers fast.
Cons: Not as well blended colors.  

3)Oil paint. 
Pros: Blends well, combines colors well.
Cons: Takes forever to dry, messy, and if you aren't careful could get on clothing and stain.