i don't use both daikin and mitsu so can't comment..currently used two units from Hitachi..one more less than 6 years (non inverter)..so far very good..silent outdoor unit and energy saver..the recent one got inverter..silent outdoor unit..but the downside the price quite expensive from the two brands mentioned..but nevertheless i'm very satisifed.

if i had to choose between mitsu and daikin..i prefer daikin