I’ve flown on Bangkok Airways a number of times: extensive network, good prices, and a feeling that they care about their passengers. Reasonable legroom on the planes and catering they don’t charge for, competent pleasant staff on the ground in the air. Punctual and reliable.
And two more really good points:
(1) A measure of pampering while you wait. Free free basic refreshments in departure if it’s an airport they own, otherwise there’s a Boutique Lounge, a kind of "Business Lounge Lite" for economy passengers with comfortable seating and free nibbles and refreshments.
(2) If you fly with them even once you qualify for the basic level of Flyerbonus membership which gives you an increase in permitted checked baggage allowance.