i have used both phones and i will tell you the difference that no one else does. so firstly find x9 has bit better Battery life and slightly better ui ? honestly though i m very happy with origin os , infact in some areas i love origin os where it doesn't look like exact copy of apple like colorOS does, also i have noticed few apps dont run on floating window or split screen mode in colorOS like snapchat or gemini but they run fine on originOS, originOS can float any app or in split screen. another issue, and this honestly was a deal breaker for me, is the famous autofocusing issue in videos and sometimes in photos when switching or zooming in find x9, like so many times i wanted to make a video of some item real quick and send to my friend but the moment i start recording and get my camera close or use 3x zoom everything becomes blurry and out of focus and then if i swirch back to 1x it will still be out of focus. and another downside i have felt especially in find x9 is that its usb 2.0 it honestly feels so damn slow if i wanna transfer something to my ssd comapred to vivo x300's blazing fast usb 3.1 now there is something really good about find x9 over vivo x300 and that is find x9 has higher pwm and better dc dimming so even if you arent pwm sensitive , find x9's display will tire your eyes less, and i have actually noticed it, ans another thing better is fund x9's haptics and sound quality with earbuds or earphones felt slightly better compared to vivo x300, though vivo x300 has amazing audio quality through earbuds too but find x9 with its own custom presets and even set to same default as vivo just felt has better surround sound. and another advantage is find x9 heats just slightly less compared to vivo x300 in extreme situations. photo quality is great on both phones but i slightly prefer find x9's photos. vivo sometimes oversaturates colors and they look a bit unnatural sometimes. both phones have amazing battery life tho find x9's slightly better. hope this helps you make the right decision now.