"The Real Deal"
If you're on the hunt for real Thai food, then canteen style nosh served in a temple compound is pretty much the holy land. Follow the scene of sauce to this hidden area behind the temple, and instruct the server which curries you want to sample.
As is highly regular in these kinds of situations, if you don't arrive when the food is freshly prepared, it will be cold. Deal with it, and kick yourself for planning your day so badly or being stuck in traffic. The curries here are pretty much spot on and not too sweet. It's cheaper than anywhere else around for this quality of food, and the vibes are super authentic.
These recommendations are just personal opinions based on my palate, things change, chefs get fired or replaced, places open-close, relocate, so take it all with a pinch of MSG and discover your own gems too. But please do try a few of these, they have been researched exhaustively.
"Tastes are subjective, so take everything with a pinch of salty tears"