If someone asked me where to go for a nice sit-down meal (say, with someone you'd like to impress) in Waco, I would probably send them to Bangkok Royal. Their new location is spectacularly nice, so much so that it feels like a fancier restaurant than nearby Diamondback's.
Anyway, there's no question that this is the best Asian food in Waco. As a huge fan of spicy food, I love the different curries on the menu. They're even willing to make things spicier if you'd like a three-star dish to be more like a six. They even have tofu, which I love, even though I'm about as carnivorous as it gets.
Even the take-out from Bangkok Royal is nice. Every time I've gotten curry to go, it even comes in an awesome plastic tub instead of the usual "please don't ooze curry on my car seats" styrofoam box that most places give you.
The downsides? Sometimes the service is a tad slow, and I have a bad habit of ordering the pricier things on the menu. I guess it's the fact that there are seafood dishes and tasty appetizers to order and, well, I can't resist. They have some wonderful inexpensive lunch specials, though, which sort of makes up for it.