sorry about this. footnotes added below.

Comparison Table

Glasgow HardSploitTigardJTAGulatorHydraBusGoodFETGreatFETBusBlasterBusPirate
UART
SPI
Parallel
I2C
JTAG/SWD
Logic AnalyzerThrough Bitmagic 
ExtensibilityFPGA FPGA FTDI MCU MCU MCU MCU CPLD MCU 
InterfaceCLI,API CLI,GUI,API CLI,GUI,API CLI CLI CLI CLI CLI CLI 
I/O count ¹ 16 64 14 24 44 100 
Cascading ³ 
Indep. I/O ⁴ 2 banks 8 banks 1 bank 1 bank 1 bank 1 bank 1 bank1 bank1 bank 
I/O Voltages1.8-5 V 3.3 V, 5 V 1.8 V, 3.3 V, 5.5 V 1.4-3.3 V 3.3 V 3.3 V 3.3 V 1.5-3.3 V 3.3 V, 5 V 
I/O Speed ¹ ² 100 MHz 25 MHz 25 MHz 15 kHz 42 MHz 1 Mbps 50 MHz 6 MHz 1 Mbps 
USBType C Type Mini-B Type C Type Mini-B Type Micro-B Type Mini-B Type Micro-B Type Mini-B Type Mini-B 
Open Hardware
Cost$130 $320 ⁵ $39 $170 $80 $50 $100 $45 $37
¹ In perfect conditions
² In Hz for target I/F bottleneck and bps for host I/F side bottleneck
³ Able to connect multiple devices together and synchronize them
⁴ I/O banks with independently controllable voltage
⁵ Unavailable at time of comparison