[Thor Laserpunch]

Honestly I think your best bet is the 6" basic/kiddie line for general play value, character selection, and cost effectiveness.

The Legends/Infinite/Universe/whatever 3/75" line is also pretty expansive and has good character selection between both movie and comic versions. I think they only made up through Civil War as far as movie figures go though, and getting the comic version of someone like Thanos is probably more than you wanna spend on a toy your kid is gonna roughhouse with, but generally they are good quality at usually under $10 a piece.