Honestly whatever head unit you want. The big two are kenwood and pioneer, sadly alpine is kind of lacking now a days. Try to make sure it has at least 4 Volt pre out, 2 volt is okay but you have a higher risk of getting noise in your signal to your amps.
Me personally I would go kenwood. But then again, with my G I'm going with this baby.
https://www.phoenixautomotiveinc.com...r-infiniti-g37