Hey @Leo M Christensen, I don't fully understand some of your abbreviations (like m2, etc.) - but generally the way I would look at it is if you're investing for cash flow or appreciation. If you're following the BRRRR strategy, you're keen on how much cash you can pull out from each purchase to redeploy. In the US mortgage market, 6+ multifamily unit is considered a commercial property (5 units or more are commercial here). In commercial loan situations (in the US), the property generally has to support the mortgage payment, expenses, etc. from the income it generates. Therefore, you'd probably favor the property that has the strongest cash flow. If commercial loan situation is not true in Denmark - then probably look at which property can appreciate quickly (so long as it's profitable enough) so when you refinance, you can pull out the largest chunk of cash.
The other way I'd also evaluate this is which property has the best return on equity: as in how much free cash flow you get per dollar invested. For instance if I was looking at property that cost US$100,000, required 25% down (equity) - so $25,000 in this case, gross rent of $1,000 and monthly expenses of $300 so net rent after expenses of $700. So you're getting $700 for investing $25,000. So your annual return on the $25,000 is 33.6%. That's ($700 * 12 months) / $25,000.
If you can clarify the numbers above, happy to revisit.