Most of those are pretty similar. Just slight differences in the gpu's for the most part. I personally would probably get the msi out of that batch, but that's just my liking msi as a brand. I think the acer is probably the best bang for your buck, but I don't like acer as a general rule. The samsungs all look comparable.
I would use notebookcheck (http://www.notebookcheck.net/)
to figure out the best gpu combined with any other nice features you're looking for out of those.
Not the most helpful, but hope it helps.