Should I buy a refurbished 14 pro max for £490 (not from Apple but sold on Amazon) a refurbished 14 pro for £450 (again not sold by Apple but brought on Amazon)or a brand new 15 for £580

The pro and pro max says it will have 80% or better battery life so that worries me a bit but I’ve heard the battery can still be good even when on 80%

Not much to say about the 15 as it’s just a normal brand new iPhone

I currently have a 12 and I’m fine with the charging speed so I’m not sure if the 15 is worth it as the only plus I’ve heard it has over a 14 p and pm is the usbc,