Hi

From experience, of the larger displacement bikes (Shineray), the 650 & 400 sold by Mash in their range, also Herald sell the 400 in their range also. Benelli, seem to be very good as well, ignore some of the woes from before chinese ownership, a good range of bikes from 125 to 750 cc. I have the Imperiale 400, as I just like the look of it, it rides well as well. Linked, to Benelli, the Keeway range of bikes/scooters seem to be benefiting from an uptick in quality and reliability. Having said the the nipper and her friend have superlights, and they are lovely little bikes.

As for Zongshen in the UK, you're really looking at the Sinnis Terrain, FB Mondial bikes (quite expensive for chinese bikes), Rieju Century 125.

Depending on what style you're looking for, the their are others to choose from sold by Lexmoto, AJS etc.

To be fair, it's relatively rare these days for the chinese manufactured bikes to be particularly unreliable, and poor quality, they have improved considerably in general over the last few years.