I think TIKTOK- mainly because your videos go everywhere and to everyone instead of on youtube and Facebook it takes time to get to everyone unless you have a good following. I have always gotten more views on TikTok.
According to me short video platform like tiktok, reels in Instagram and YouTube shorts are best for uploading videos
As now a days people have less time so they want good content in just 1 minute, do they just scroll through short videos as they loose intrest in very short time.
YouTube is still the best for me, not because I've spent hours in it than the other two, it's because of the system they've come up to. The videos uploaded, the contents filtered, the payment to those creators and many more aspects