Can't address Sapphire Princess - but in March, 2023 we took Oosterdam from BA to Fort Lauderdale (via Santiago). It was marvelous. Next year we're going to take Oceania from BA to Santiago and do the route that adds Antarctica. I think the question comes down to which type of ship you prefer. I believe Oosterdam is smaller than Sapphire Princess - with less "bells and whistles". However, we appreciated the smaller size and the ability to have great viewpoints from the Promenade Deck, the Crows Nest etc. In looking at the 2026 itineraries - it looks like the Princess cruise does Antarctica, but skips the Chilean fjords. We found that part of the cruise to be really interesting because the captain has some leeway to where he cruises. It also adds some interesting ports. Best of both worlds would be the 22 day cruises on Oosterdam that do both Chilean Fjords and Antarctica!