All else being equal, Esan Classic is newer and spiffier than the original Lers Ros across the street. Same restaurant group so maybe just go by which menu is more appealing at the time.
If I lived in LA, I’d skip Thai and go to Burmese Kitchen, but if you’re in SF and craving Thai, you can eat well at those places.
I’ve gone back a couple of times and forgotten to post. Consistently good.