How are these counties for whitetail hunting?

Just depends on where in each co you are in. Some areas you couldn't give me for free while others could produce some real giants. I've seen several 180 pluses in Mitchell co. Scurry co can also be awesom while Nolan is probably the weaker of the 4.

These four counties form a square, is there some sort of topographical change that makes some parts of it great and others only fair or is it the management of individual places?

I think the two northern counties have alittle bit different soil types that make them more prone to agricultural. I also think that further north you go there tends to be larger tracs of land with less pressure. The key is to find a very quiet area in one these counties preferably in Mitchell or scurry in my opinion but fisher isn't bad either that's very low pressure and be ready to wait a good while. The area has produced some real giants though.

Scurry County deer. Some of the images were extracted from video so they're sort of fuzzy.

Drought has really done a number on the deer herd in Fisher county. They are still there but I wouldnt doubt some areas are less than a deer per 100 acres. Higher populations in Nolan and eastern Mitchell but rarely a wow deer in those areas. Parts of Fisher and Scurry have MD as well.