The Honda NX500 is a great middleweight ADV with a refined engine, good ride and handling and being a Japanese bike, it will last you a long time while being relatively easy to maintain too. Its asking price is quite steep, but for some, its reliability and low ownership costs are worth that tradeoff.
Coming to whether you should buy a more exciting big bike, that is a question only you can answer for yourself. Big bikes are exciting, capable and striking things to own, but also have high maintenance costs, lower fuel economy and any replacement parts you might need are usually pricey and not readily available.
If that sounds like something you can live with, then you can save up and buy a bigger adventure bike like the Honda XL750 Transalp, Triumph Tiger 900, Suzuki V-Strom 800DE or Ducati Multistrada V2.