For someone who has not been successful at BTO and is forced to look at resale flats, is it better to look at flats which just reached MOP (which tends to be overpriced), or flats which are older?

Lease decay is a consideration, so we'd look at newer flats even if they cost a little more. Older flats depreciate faster, which may more than make up for any potential savings.

That said, affordability, size, and location are the main points of comparison to focus on. This article may help (https://stackedhomes.com/editorial/newly-mop-ed...)