Connection
Most interfaces here connect over USB, and the socket tells you less than you'd think. Focusrite's 3rd and 4th Gen Scarletts have USB-C but still run the USB 2.0 protocol, so a USB-C cable won't make them faster. Earlier Scarletts like the 1st and 2nd Gen 2i2 use a square USB Type-B socket. A few boxes do need USB 3, including the Apollo USB models, which also run on Windows only. Bus-powered units take power from the same cable. Class-compliant ones, like MOTU's M-series and PreSonus's USB interfaces, work on a Mac without a driver.
20 models we cover.
Focusrite
USB$55–$80 typical ask
8 on eBay
Focusrite
USB$70–$110 typical ask
63 on eBay
Focusrite
USB$95–$180 typical ask
106 on eBay
Focusrite
USB$70–$130 typical ask
24 on eBay
Focusrite
USB$95–$160 typical ask
45 on eBay

Focusrite
USB$110–$180 typical ask
95 on eBay
Focusrite
USB$190–$290 typical ask
108 on eBay
Focusrite
USB$180–$290 typical ask
21 on eBay
Focusrite
USB$400–$600 typical ask
17 on eBay
Universal Audio
USB$500–$700 typical ask
20 on eBay
Universal Audio
USB$550–$825 typical ask
16 on eBay

MOTU
USB$190–$370 typical ask
33 on eBay
MOTU
USB$270–$300 typical ask
16 on eBay
MOTU
USB$675–$700 typical ask
13 on eBay
PreSonus
USB$50–$75 typical ask
194 on eBay

PreSonus
USB$90–$180 typical ask
19 on eBay
PreSonus
USB$110–$150 typical ask
6 on eBay
PreSonus
USB$130–$200 typical ask
6 on eBay
PreSonus
USB$330–$390 typical ask
3 on eBay
PreSonus
USB$480–$490 typical ask
1 on eBay