I created a new forum category here to start building an open, crowd-sourced database of latency round-trip loopback measurements.
The Presonus AudioBox devices significantly outperform many of the devices that I’ve tested so far. Presonus’ Windows ASIO driver seems to be fantastic, on par with RME. Given that you can buy an AudioBox USB 96 for $85 (USD) at Sweetwater, I currently consider that the best value for the money. At $59 (USD) on Amazon, the Neva Uno appears to be another great low-cost option. It also has built-in virtual channels which make DAW integration a lot easier (no extra third party tools).
I’m sure there are many other great options are out there, and many more to appear in the coming months.