The camera will mainly be used for landscape photos. And my budget is $400-$700. I'm just trying to decent camera around that budget that I can learn with.
For landscape you can pretty much choose any of the following Nikons
D3300, D5200, D5300, D7100
All these cameras have a very strong sensor with good dynamic range, very good image quality
If you would like to do HDR in the future then you might want to go for the D7100 for the bracketing capability.
If you just want to find a scene and shoot it and don't want to spend too much the D3300 with a basic kit lens 18-55mm will do the work just fine.
The D3300 is the basic Nikon DSLR, its low on features but the image quality is about the same as any other Nikon camera because of the wonderful sensor in it.
What really will produce good landscape images will be your own skills and good sharp lenses.
So choose the camera and we will be able to recommend you good affordable lenses for landscape like Nikon 35mm 1.8G or Sigma 17-50mm 2.8
But for the beginning you can start with a camera body and basic kit lens.
You were suggested mirrorless micro four thirds cameras like the Olympus EM5, its a nice camera but has a smaller sensor then the D3300 or other Nikon DSLR, the advantage here is that the bigger sensor will give you pictures with better image quality. But the main factor with producing a good picture will always be the photographers skills