We is heat the primary need? Is ac needed? What are your most important features? Green? Value? Performance?

Natural gas is our preferred if available for value and performance with a diakin system but we have a/c as well. If ac is not needed radiant heat (underfloor) is a wonderful choice, efficient and effective. A hydronic system. If no ac were needed we'd install this every time, handsdown.

To me, ground heat pump means a geothermal option- that's very site specific and in our experience it is costly to install and the buy back (the amount of time the savings take to repay the cost of the system) does not work out. It may be different for you in central France. I can't wait to see the other answers you get!

Thanks Shannon - so far only yours - There is no natural gas available where we are (will be using bottled gas for hob use). After much agonising we have decided to install backup radiator points throughout (only actually install radiators as/when we feel we need them to back up the heat from woodburners (5 and 8 watt output), underfloor is definitely on the cards for areas where we will have terracotta tile - still making enquiries as to the effect on parquet blocks - if this considered alright, then it will be underfloor throughout ground floor. Probably the better option is to live through a winter with the woodburners and see just how far, and how, the warmth travels through the house (approximate 140 square meters stone house). To answer your question of 'motivation' - i guess we are looking at environmental as well as value and performance - Not demanding much are we!!