Both are doable, depending on your goals. Do you want some extra hp and already enjoy the car? Jb4 works great. Not as expensive as an ecu but also allows you to take logs and increase performance. Also easily removable.
On the other hand, like
@Rodtheviking said, it may seem easier to have an ecu tune as you just get in and drive. You don’t have to connect or check your phone, it’s just your ecu. At the same time you would probably want a jb4 to check your logs regardless, so starting with a jb4 is never a bad option.
Many people dd both a jb4 and the highest performance tune you can get with cpi/wmi. It’s really up to your budget and what you want out of the car.