In most cases I'd argue for the former. What if the fleeing pcs are just trying to lead the goblins into a trap or an ambush?
Staying in their easily defensible 'home base' makes a lot more sense than running into an unknown open area.
If the pcs have left behind dying (but not dead) party members, the goblins might even be better off to keep them alive to be able to threaten to kill them should the other pcs return.
Eating prisoners can wait until they feel they're safe again.
My goblinoid/giant class type monsters will typically kill, mutilate and eat (parts of) fallen foes, including PCs, as part of their victory celebrations. Human bandits might take PCs for ransom, if that seemed a good tactic and drow in or close to home territory might take them for leisurely torture. Cultists might take PCs for sacrifice. I try not to stretch credibility by keeping fallen PCs alive, though - it's different if they surrendered; surrendering enemies will rarely be killed immediately (except by the PCs!)