Living in Thailand, it's a bit hard to find a decent beer. Chang is my usual tipple. The new Chang Draught is not bad, indeed quite good, though quite how you make a real bottled draught beer is beyond me. For a bottled beer, I still prefer Chang. The restaurant Dairy Hut in Phuket Town serves good Draught Chang. I tried San Miguel recently - a Philippino beer (brewed under licence in Thailand). Also tasty, but quite a bit more expensive than Chang. I tried the Red Horse beer (also by San Miguel) one time - strong and scary. I swear I was not the same for several days after drinking it...
Singha Beer is the Thai Beer, but I never drink it, and Lord knows why they decided to launch a Singha Light. Leo has it's fans, some say it tastes "hoppy", like a German beer. I disagree. Tiger Beer is not bad, Heineken is certainly drinkable and gives a less severe hangover than Chang. You see, there's plenty of choice, but most of it might as well be thrown straight down the bog, cutting out the middle man.
This blog has some interesting analysis of beer in this part of the world:
(if you somehow found this post, it's very old (2006)) I still like Chang though!