I’m building a VTOL tail-sitter duo rotor with thrust vectoring. Does anybody have advice about about the most adequate autopilots solution for this platform (Ardupilot or PX4) ?

[losawing (letpi)]

I dont know about PX4 but you can find several dual motor tailsitter with thrust vectoring

Dual-motor tailsitters

This is a place to discuss support for dual-motor tailsitters with ArduPilot. This is for any fixed-wing airframe which sits on its tail to startup, and has two forward motors for thrust. The motors use differential thrust for roll when hovering, and elevons for pitch and yaw. Support for this type of airframe is in master now, but has only been tested in a simulator. We’re now waiting on the first real aircraft flight tests. Mark Whitehorn may well get there first, as he already has one flying…

belly sitter are supported from plane 3.8.3
examples can be found posts 782-893-995