It's hard to say, not saying Anker would produce a bad product. But having to rely on a torch that has a built in charger has more chances of failure. If you had portable charger and a separate torch, if one "dies" you won't be completely screwed If your phone were to die and portable charger malfunctions, at least you wont be left in the dark if you had a separate torch. If your torch dies, and charger works...you'll have longer run time to be able to call someone.
As I tried to express before there's also an issue on size vs capacity my friends and I at a minimum carry a 10000mAh pack each when going out. Sometimes I even carry my 20000 because its the only one that I have that has QC (hence small backpack and separate torch). Whereas my friends have the 10000 speed variant. Not many in my family use the lipstick sized type due to not having enough "juice" as well.