The latest inverter driven units by Mitsu and Daikin are where it is going. Don't buy a cheaper fixed rate compressor product; they are simply not as economical.
People are jumping on the inverter bandwagon into thinking that inverters with all their fancy twikerwee must save them money.
This is simply not the case as inverters are very inefficient at full speeds and during winter they will need to run at full speed for most of the time. Thus the supposed energy savings are nonexistent. Plus they often need 'top up heaters' in the immersion during cold weather further driving down energy efficiency