I have been using both for a while. It's interesting when I'm seeing what's available, I check Uber first to see the price and then check Didi, which most of the time Didi cheaper. Although, if I go back to Uber for another check, it seems to fall to about the same as Didi. I wouldn't surprised if their algorithm is picking up people looking at what's available, and then not going ahead with a booking, and working out they might be looking at other options.
Although our most recent experience with Didi in Sydney a week ago, which was bad, left us using Uber all weekend. The Didi driver seemed to have accepted a ride with a couple, and then accepted us after that as a second ride after he had dropped off the first couple. The problem was we were all standing at the same spot at Central Station, and when he pulled up we all questioned who was his ride. When he said the other couple, and "bad luck, cancel the ride", we decided to give Uber our business.
