Much discussion has already been done,

(sorry if it's not the very latest iteration)
Red Bull system looks good as it can feed the centrum of the diffuser well
I would think this has less horsepower lose than McLaren's one as the position of the pipe is slightly more neutral.
McLaren's one

I would say it has less drag than RB one and probably goes more efficiently in the zone of router/diffuser deleting vortex. I think this is the best solution at least for the external zones of the diffuser to work and make downforce.
I vote the McLaren's one