The main supplier is YuTong but AlexanderDennis/BYD collaboration is second with Daimler in third place. Of course battery electric buses appear to be more economic, but that is because the battery bus carries ten times less energy than a diesel bus. So it works until lunchtime. It cannot do the 300km 18 hour shift that diesels do. It is essentially a dodgy short-term answer. Hydrogen buses do store enough energy and can compete with diesel so are rapidly increasing now in Germany and UK but will take time to compete with the mass manufactured battery bus. The main problem is that bus trips are falling everywhere and on the road to extinction as citizens find alternatives, like scooting or jogging.