If you've read on the World's On-Time Performance for Airports 2018, here is where you can find the latest annual rankings on world's airlines.
For airlines, on time is defined as arrivals that take place strictly less than 15 minutes after scheduled arrival time, including cancellations.
Let's have a look at the OTP performance score for Southeast Asian airlines as listed within the top listed within this category:
Note: *OTP measured June 2017 - May 2018
Source: OAG Official Website