Either Mitsubishi Ecodan or Daikin Altherma IMO. Although there are a few good ones in the market there are a lot of trash. Id stay away from NIBE (just my personal opinion). Panasonic/Hitachi units are apparently good. All these units will do as they're supposed to, it depends on the system design and operation that will determine their performance.
If you're doing the job from scratch then try contacting Nu-heat (they will usually design and spec the equipment FOC as long as you buy from them).