Heating decision: air-to-air or air-to-water heat pump

There are also regular loans, and when building new, you usually get a few thousand extra financed through the bank. However, with 3.5-4% interest and 1500-2000€ per kWp, I would question the profitability. The self-consumption in summer is quickly covered; every additional kWp relies mainly on the feed-in tariff and only to a lesser extent on self-consumption in winter. You really have to look at the specific prices.

Since the whole thing has now drifted somewhat towards solar, here is my core question again.

KFW40+ with photovoltaic and small storage (can't find the size requirements right now)
-> Does an air-water heat pump make more sense as it is more open for the future?

I tend to say that the underfloor heating provides a nicer warmth than air heating - do you agree?

Since the whole thing has now drifted somewhat towards solar, here is my core question again.

KFW40+ with photovoltaic and small storage (can't find the size requirement right now)
-> Does an air-water heat pump make more sense as it is more open for the future?

I tend to say that underfloor heating provides a nicer warmth than air heating - do you agree?

Basically yes.

How much more expensive is the air-water heat pump solution compared to the air-air heat pump?

I (still) don't know the exact difference, as the offers were from two different companies. Just a gut feeling - the underfloor heating will surely be a bit more expensive - are there any reference values?