For value I am very happy with Kumho. Personally I like them better than (don't lynch me) the BFG ats and nitto ats I had previously. They ride smoother handle better, and do better in the sand. All 3 were different sizes so thats just my opinion. Never had any of them in mud or snow.
The 325/60/18 you mentioned is $215 at tire rack. Decent price for 18s. Kumho list them as 33.4x13 actual size. Not a mud tire, but good all round tread.
Comparison of them and a dozen others:
Here is the tread next to a BFG
Here is the sidewall of a 325/60/18. The nissan guys have good things to say about them. The sidewalls of 18s are differnt than the smaller ones.