GSHP Vs Air to Water

I know this might have been discussed before ad nauseum but since technology is constantly moving and improving I just wanted to see what peoples opinion is of today.

I am planning to build a new house in the country on a 1.25 acre site and I need to choose between Air to Water or GSHP for all heating and hot water. From what I hear GSHP have a better overall COP on average over the year, are more reliable but are more expensive mainly due to the fact you have to install either a ground collector or a bore well.

Is this still the case??

I know all the manufactures are pushing A/W now but my thoughts are I will be drilling for a well anyway on site for drinking water so it wont be as expensive to drill if they had to specifically mobilise just for the GHSP. Also I will have diggers on site for percolation area so if I decide to do a collector array again it should cost less.


Or is it the case A/W now are just as efficient and reliable as GSHP....


Thanks