Melting halibut pellet for Barbel feeder fishing: Krill or Nature, which one to choose?

Tackle and Gear used :
Rod: Korum Big Water 12ft 2.5lb
Reel: Korum Neoteric FS 5000
Line: Korum Barbel reel line 12 lbs (33/100)
Feeder: Korum River 150gr (5oz)

Bait:
Halibut Krill & Nature Pellet