Personally, I suggest you take the train, which is less expensive, can catch up with the time and is not slow.

K1162/k1159 times, 14:20 starts in Yishui, arrives in Zhengzhou at 0:02, hard seat fare is 87 yuan, hard sleeper162 yuan.

1552/ 1553 times, leaving at 0:42 in Zhengzhou, arriving at 4:05 in Gaoping, and the hard seat fare is 30 yuan.

If you miss the train in Zhengzhou because the train is late, you can only spend the night in Zhengzhou and take a bus to Gaoping the next day.