Ideal GPS setup for 1 meter surveys

Hi all, I am working on a new Hexacopter build to perform grid surveys with 1 meter line spacing. I am hoping for a relative accuracy and repeatability of <15cm between lines in calm wind conditions. After comparing results from Tridge’s GPS roundup I am leaning towards two possible choices; either a moving baseline setup with dual Holybro F9P’s (helical) or a Emlid RS2 Fixed base with M2 rover. Does anyone have experience or comparisons in relative accuracy between moving baseline RTK and fixed Base/ Rover RTK? What would be the ideal setup to achieve the highest possible accuracy (relative, absolute and repeatability)? Thanks.