No question, the best for outdoor scenes is Vue6, even film Companies are using it because of how good it is!
Some major landscape shots in Pirates of the Caribbean were done in Vue!
If it's comics you're after doing then you might find Comic Book Creator useful, it's available here or it was!! If not, you can get it at planetwide games.

Injustice will be avenged.
Cofiwch Dryweryn.