I don't know about those other laptops but I have to say the z is by far the best laptop I have ever owned (i've gone through 5 or 6). It's just so powerful and yet so small and lightweight. At the time that I got it, I couldn't find any other <15" with a 1920x1080 screen (ya its a bit small on the 13", but having that extra screen space for code is beautiful).
I am with AsherO though, I wouldn't spend that much on a laptop. Although if you use it all day every day then it can be justified, same as a great office chair or mattress etc.