Idk what powerhead, but your system looks great!!!
I'm using a marineland 400 with a 360 moving deflector in a 29 gallon and the flow is barely noticeable. The plants move, but it's very gentle.
The one I picked was pretty cheap compared with others. The directions for assembly are useless, but I found a YouTube video.
I think for price you might consider one of the marineland powerheads
(Friend of Bill W., One day at a time)