I like Iwata. I have two, one my original gravity and the second a siphon
Iwata Eclipse HP BCS Dual Action Bottle Feed Brush ECL2001 Includes Brush, Hose, Cleaner, Paint https://www.amazon.com/dp/B000BQKFA8/ref=cm_sw_r_cp_api_i_4F540QBS4ER7H9RC60KE?_encoding=UTF8&psc=1
The bottles, i purchased an off brand that work as the Iwata bottles can be pricey. The thing i discovered is the metal tip bottles don’t work with it so look for plastic.
Hope that helps. :)