Ok, you are looking to photo shoot nature and outdoor things. All cameras can take awesome photos, one better then the other mmm i don't think so it all depends on how your are going to use the camera and what lens you have. For the situation that you planning to put the cameras in, all three would do great. It all depends on how much money you have. Now if you put kit lens on these cameras your photos will not come out that great, the lens make the picture!
If you are saying that you can get the 5DII with the 24-70mm F/2.8 L lens then get that, if your other options leave with out the $$ to buy a L lens. According to what you are planning to do with the camera the 5DII is still the best option for the cost.