I avoid flying Air Asia because of all the add-on's to the ticket price.
Note you can purchase extra weight up to 40kgs/passenger with Nok Air
I often fly Thai Smile W9 because they are the only ones to fly to UTH ex BKK and pay extra for luggage at check in, no option to buy online, it's stupid...
All the LLC's have new planes except Thai Orient, to be avoided.