I'll go with the group and say if you're paying for F, enjoy F.
I love HKG though, so any excuse to route through there would win me over. Five hours would be more than enough time to hop into town, have a tasty meal and maybe see some sights or buy some souvenirs.
You don't mention the time difference on arrival into ICN, but it seems to me AC could provide hit or miss service and an okay product while SQ would provide consistent good/great service and a known, quality product.
Plus YVR-ICN is on a 763 - not all of AC's 763s have the new C-class product so unless I missed, something, you could be at risk of a pretty "blah" in-flight experience.
Looking at the schedule for random dates in June, it would appear the arrival into ICN is 15:50 via AC and 17:45 via SQ/OZ (I'm assuming this is what you're considering). Two hours difference wouldn't be enough for me to choose AC C over SQ F.
Off-topic: lucky - out of curiosity, which *A lounge do you find nicest? Is the SKL *A?