Me, I'd go for the immersion suit. It's difficult to leave behind when you're wearing it. That gives you usually enough hours for SAR to find a live body, especially if the PLB is on your person.
Aviation immersion suits are expensive; suits for the surfing and kayak folks might be adequate for a lower price.
A raft is a bonus, but there's lots of ditching stories where they don't make it into the raft.
Do check the marine forecast for water temperature, wind and wave height.