I thought charge rates were dependent on the charging block itself? Also if it isn't dependent on just the charger itself, how warm is your phone when it's charging? Warmer phones take longer to charge because if it is being warm before charging commences, that means the battery is being worked hard from drainage.
Future Phone: Don't know yet?
Current Phones: Xperia Z Ultra 6806
Past: Samsung Galaxy Note 3 AT&T [Unlocked], LG Optimus G Pro AT&T, LG Optimus G AT&T, LG Google Nexus 4, Samsung Galaxy S3 AT&T, Samsung GS2 AT&T, Sony Xperia ion AT&T, Samsung Infuse AT&T(First Android Phone), All iPhones before that.