9th level Elf feat. Perception vs spell slot

Ninth level sparkling targe magus elf unsure about Elven feat selection.

At first level I took nimble elf, because I utilize a fortress shield and speed is such a thing in this system.

At fifth I took Elven instinct for the perception initiative boost. Currently have +2 in wisdom. At ninth level my perception is (expert) +15, although I have a greater eye slash tattoo, which brings my perception on (sight based) initiative rolls to +18.

I am debating retraining that Elven instinct slot into Otherworldy magic, which would allow me to fill the new ninth level slot with Otherwordly acumen.

I do have three extra spell slots currently from a psychic dedication and basic spell casting. The question is….which would the community say is more valuable? A +2 to perception based initiative rolls or a second level spell slot/extra cantrip?

Thank you as always!