Which to make for in Cape Horn area?

[rigormortis]

Hi folks:
Would appreciate some advice regarding the passage from Mar del Plata to Beagle Channel. I intend to sail down the Argentine coast and not too far out, either, probably not stopping unless wind on the beak (guaranteed in sailing). But my question really is, should I not check out of Argentina and make my last port enroute, Ushuaia, or should I clear out in Mar del Plata and make for Puerto Williams, Chile? I realize I will have to report to Argentine land stations, regardless. No concern there. Not going to Malvinas/Falklands so no concern there either.
I will attempt the chicken’s route around Cabo de Horno so I need to go to Puerto Williams and I need to go to Ushuaia at some point to pick up fresh stuff before heading up the Beagle where, as Mike Tyson says(not about the Beagle), ‘Everyone has a plan until they get punched in the face’.
It's a simple, which is better stop, first?
I have no concerns with visas or boat visas. I’m going to be ok there. Noonsite doesn’t really have the info I need. Anyone who has been that way recently could give me some good advice and I would appreciate it.
Pete

[Cpt.Blood]

Try this. ESTRECHO DE MAGALLANES