Haven't been to CN but just returned from #5 at CTI. Their spa is rated one of the top in the Caribbean. It is wonderful. The setting is beautiful and very relaxing and the staff amazing, as is all the staff at CTI.
What we like about CTI: Amazing staff and service. Many of the staff have been there for years including coming back after the resort was shut down for a year (?) during renovations. Incredible food. Private beach--no vendors except for the one that CTI allows to set up outside the gift shop and then the vendors on Beach Party Night. No jet skis and motor boats buzzing the shore line. The other guests we meet. The gorgeous ocean views as the resorts sits almost directly on the water.
Different people have different preferences; CN is my favorite of the four, but there are others who have been to all four who prefer CTI. Spend some time on this web site reviewing photographs and information about both resorts and choose the resort that appeals to you more.
I know everything, and I'm always right (just ask my husband).
I prefer CN by far. We went to CN for our honeymoon, then went to CTI, and now we are going back to our beloved CN. The atmosphere is completely different at CTI. It is a nice place and as mentioned above, the spa is fantastic.
CN has a more 'Jamaican' feel to it. I felt like CTI lost a lot of the culture and is more of an American type resort. CN also has a MUCH better beach. CTI has more rough water where CN is in a bay so it is crystal clear and smooth with soft white sand at your feet.
We didn't feel like CTI has as much to offer entertainment wise either. We aren't huge party people at all, but it would have been nice to have some beach games or something other than a few games at the pool bar.
At CN there is always an opportunity to do something if you feel like it.
Let me know if you have any more questions and I'll be glad to help