Have you tried them out? I'm sure both are nice. I've heard the Zenith is a very smooth medium fast and the NRX is a fast action beast. They are probably different enough that you need more than a forum to decide between the two. There are a lot of expensive rods out there, pick the one you like best.
I was shopping for a rod in that weight range recently and ended up coming home with the NRX because the way it cast for me and I felt it had the backbone to do what I wanted to do (throw bobbers with a light rod).
But a close runner up was the Burkheimer Classic and if you are in the Seattle area you should try one out (PSFCo has one in the shop).
Its a malachite kingfisher,i live in south africa.
I was tying flies in my cabin and heard a thud at my window,the bird stunned itself.I held it for about 20 min in my hand until it recovered and flew off.
Magnificent bird this!so glad it happened to me.
They are both great rods. I really like the action of the Zenith's. They were on closeout because they changed the reel seat. If you can still find one at the closeout price that would break the tie for me.
The zenith is a tough rod, just for a baseline hardy tests each rod series in a blank bender. Well the zenith in a 7 wt did not snap after ten runs to 32 newtons of force. Apparently most blanks break at 18 newtons. Btw if you really go into that Korean=poor quality thing, im pulling q Yellowstone anglers line: which brand car do you drive?
However I personally prefer buying North American.
A closer comparison would the 4wt Zenith and 4wt Scott Radian. I have the Radian 905 and love it. It replaced a Zenith 905 which was also great, but after trying the Radian, I was sold on its amazing feel and accuracy at all distances. Nothing wrong with the Zenith on either score, but the Radian is just unbelievable (IMO, YMMMV, etc.). Having said that, a Zenith on closeout would be half the price of a Radian. Hard to pass that up.