So E couplers make the majority of railcars rollin' through N. America. Most are your standard non-shelf; double shelf ones are going to be found on your tank cars but aren't exclusive to tanks. I've had standard low top gondolas used scrap service with one regular E and one double shelf E. Why? Sometimes it's whatever is on hand. Looks funky.
Long drawbar cars like flatcars centerbeams, certain boxcar and even auto racks can be found with bottom shelf E couplers. Short drawbar bottom shelves are showing up as standard equipment on cars like new covered hoppers in plastic, sand, cement, flyash, flour etc.
You got interlocking F couplers used on locomotives, double shelf F that are also used on tanks and rotating shank F on your rotary gondolas.
H couplers or Tightlock H are passenger. I don't know much about them.