If S8 is QC4.0 - What's the best portable charger (power bank) that's available? Anker 3.0? or any?

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If S8 is QC4.0 - What's the best portable charger (power bank) that's available? Anker 3.0? or any such as PowerIQ?

Does it matter?

If I opt for 3.0, will my S8 go from 4.0 speed to 3.0 or standard speed?

If S8 is QC4.0 - What's the best portable charger (power bank) that's available? Anker 3.0? or any?