If I needed to replace my Northface Mountain 25 I would consider the following tents. No particular order, but I would be leaning toward the Mountain Hardware tents for my specific purposes.
Northface Mountain 25
Mountain Hardware EV2 or Trango2
For a Hillberg, I would be checking out the Jannu. Pricey as I have said before.
If you can, you should check all of them out and see which fits you best for your purpose. Ask others about the tents when you are looking at them. Consider weight, features, double wall or single wall, space, Etc. I am not sure who has them in stock so you could actually look at them.
Just to be clear, I don't use a 4 season tent at all in early spring, summer and early fall. During those times I use a 3 season tent or bivy and teepee-tarp depending on what I am doing.
