The Hyosung is very common in my country. It is a nice looking bike, and when you sit on it, it feels like a bigger bike compared to the Kawasaki.
However, looking a little closer you start noticing differences in manufacturing quality. And more importantly, that extra "size" comes with weight; the Ninja carries its own weight a lot better than the Hyosung, it makes a tad more power and it weighs less, having a size that generally goes with its engine a lot more naturally.
Maintenance will be very similar in cost, I presume. However, for the Ninja you have quite a large aftermarket/avalability of parts. Not for the Hyosung.
Here, I notice one of the selling points of the Hyosung is size. Specially size of tyres. It makes the bike look like a "real sportbike". But to a real, mature rider with any experience, that's bullshit: the Ninja comes equipped with tyres that correlate to its size and power. The Hyosung is trying to look like something it's not...and it handles like that as well.