I would say the ideal is mottled sun/shade. Or early morning sun, and then shade. But a lot depends on what you have available. For ex the most convenient place for me is alongside the building which faces south/east. So I get a LOT of sun. It means I have to take care they don't dry out, and of course make sure I open the tops once they begin to sprout.

It really depends on a lot of factors. Since I'm in a colder zone, I try to use the warmth provided by the containers to speed up germination a bit. So, I put my containers in the sunniest spot I can find. Once the sprout, I may move them to a shadier spot to prevent over heating and lessen my watering requirements. I also grow mostly native plants, which tend to be tougher in my climate, anyway. I also plant out the natives quite early.

For many or us, location depends more on whether the dogs will use the containers as toys, or whether the neighbors will call the township on us for having trash visible. Convenience to the hose is also important. There really isn't a perfect location. You just need to be aware of the temperature and water needs at different stages of growth.

Martha