I was in a very similar position to you and I bought a CarboNext after advice here and I love it. I have since bought a Misono Swedish Sujihiki, which was a lot dearer, and think I actually prefer the CarboNext.
Combi stone is fine I think. I would suggest 1000/6000 or something similar.
The only other one in your list that I would even consider over the CN is the Gesshin (Uraku?). I have never seen one but they seem to come highly recommended. But still, I would say get the CarboNext. If it helps, I was expecting it to look pretty dull from all the online photos, and when it arrived I was amazed by how nice it was.