I think both are promising loam options for different reasons.
Basel, he'd presumably get lots of experience playing against men at a decent level, with some Euro experience thrown in there to boot. If they guaranteed he'd be starting I think this'd be a decent shout.
Palace, he'd likely get rotated in and out of what is a fresh, youthful side. Viera has his work cut out and when the shit hits the fan, its unlikely any manager is going to be relying on a loanee kid, so risky in that sense. 6 months if anything here I think, to avoid another Fosu situation.
Either way a loan with lots of playing time is the best idea I think, even if it were in the Championship.