Between nelo and NK both are going to be great boats. If it was my money I would favor NK. The quality of their construction is next level. They come with a full surfski footplate which I much prefer to a tiller or the tiny nelo toe pedals. Also their pricing is really good if you are interested in a marathon weight boat at $4100. Carrying and paddling a 7kg kayak is wonderful. I am not sure what a nelo would cost at that weight but I am guessing it is more.
Current Skis: Nelo Vanquish AIR, NK 670 double, NK exrcize, Carbonology Feather, Think Jet, Knysna Sonic X
Former Skis: Epic v10g3, Kai Waa Vega, Epic V12 g2, Epic V12 g1, Epic v10 double, Nelo 550 g2, Fenn Elite S, Custom Kayaks Synergy