I’ll take this one.
The Jackpot V1 has a removable ESP-32, and removable TMC2209 stepper drivers.
The Jackpot V3 has a built-in ESP-32 and built-in TMC2209s.
The connectors on the Jackpot V3 are more user friendly, and the packaging is improved (where wires or cables come or go, and the ESP-32 antenna is in a better spot.)
Thermals on the V3 are a bit better if you’re running the machine hard.
The IO on the V3 is switchable between 5V and VMOT.
For most applications and for most users there’s really no significant difference between them.
The V3 is an incremental improvement, and for most use cases is slightly better.
Ryan keeps the controller prices very affordable, so the V3 in my opinion is an exceptional value- but the V1 remains affordable. I tell him all the time he should double the price. He’d rather have the boards be affordable for our worldwide community of makers.
There are reasons the V1 will stick around. The removable ESP-32 enables things like using an external antenna (if you put the Jackpot inside a metal enclosure) or playing around with development of the firmware.
I wouldn’t have any worries about starting a new build with a Jackpot V1.