Which is cheaper, a fixed-rate
or floating-rate loan?

It cannot be said in advance. Because the loan period of a housing loan is very long, the interest expenses of a floating-rate loan cannot be predicted. When taking a loan, the rate of a loan tied to a floating reference rate is generally cheaper because the markets add the insecurity related to future interest level changes to the prices of long fixed rates.

This question should not be considered for a fixed-rate loan. A more important question is how important is it for you to reduce the loan securely on the known schedule and to keep the loan management expenses unchanged.