Never heard yongji brand but flying pigeon is real good. If you don't believe , you go Beijing and go to some old estates, you can see those old flying pigeon lying around which can be trace back to 20 or 30 years old. There' s a reason why this brand is so popular even westerner knows it. Nowadays quality I'm not sure.
永久(yongjiu, or Forever)and 飞鸽(Flying Pigeon)were like Honda and Toyota those days. While 永久has transformed itself into some modern versions, such as folding bikes,飞鸽 has for long disappeared as a brand. That's my impression.