I think The Flash has more chances to win against spiderman. But i don't think that spiderman doesnt even have a chance to win against The Flash.
Check spiderman reflexes, speed and spider sense at this video https://www.youtube.com/watch?v=rxwG0vyWsWk after 5:47. Watching this, i am not sure if spiderman couldnt dodge the flash. Any way it doesnt really matter!
spiderman can also dodge laser 3558864-3264570536-319907.jpeg.jpg
I also watch this https://www.youtube.com/watch?v=FFwM5n3jC_Q its not impossible to hit The Flash, if arrow can, why spiderman cant?