If you go up a few comments you would see my post where I basically gave my opinion on how I feel about the Chinese vs Korean/Japanese/European car debate.
Quite frankly, the interiors of a Tuscon and Sonata are not that much higher quality, if at all. I own a Sonata 2.5 and could not be any happier with it. As a matter of fact, the H6 has so many ADAS features that are not even available in the Hyundai cars you mentioned. HOWEVER, the only things where Hyundai is ahead would be the soft suspension, incredibly light power steering (personally I don't like that) and its naturally aspirated engines (turbos have a distinctive feel and some may not like it).
I do worry that your friend did not like the DCT transmission which feels very twitchy at first and tends to drive a little bumpy because of bikers and other cars cutting up traffic randomly. This, coupled with the stiff suspension, probably made your friend say what he thinks. Also please keep in mind that some people will naturally have a very negative image of chinese products based on years of unrelated experiences.
What are your priorities? Fuel efficiency (please dont compare hybrid and non hybrid models) and comfort will most likely go to the Korean cars. Features, ADAS, electric cars and stiff suspensions (which some people like) are going to veer you into the Chinese side.
