Please be aware that Kuala Lumpur has multiple airports and that these results are for all airports serving the city.
The best day to arrive at Kuala Lumpur is Saturday and it would be best to avoid Friday, as prices are on average 75.01% higher than on Saturday. (Average prices, based on 202 datapoints.)
The cheapest airline flying from Kuala Lumpur to Guangzhou is AirAsia. They are 59% cheaper than China Southern Airlines. (Average prices, based on 207 datapoints.)
The best time to fly is at around 0. (Average prices, based on 407 datapoints.)