[Nanook]

I went up and down to Udon Thani 3 times this year and always used NokAir. On those 6 flights in total I had just 15 minutes of delay, so hardly any. I would recommend them.
Although maybe next time, I would consider taking the AirAsia flight back to Subvarnabhumi, in order to avoid the taxi ride between airport just before the long flight home.