First of all the 924 and 944 are COMPLETELY 2 different cars, I don't know how you put them in the same basket. The 944 started with a 2.5 litre then later on with the S2 3.0 variant and a 944 turbo variant (951). The 944 S2 3.0 morphed into the 968 and the 968CS was voted as the world best sport car in the early 1990.
I've owned and track 944 S2, 944 turbo and 911, my least favourite would be the 911. If I have money and room to buy a Porsche now I would be looking for a 944 Turbo S (1989-1990) or a 986CS. But each to their own. On second thought I probably buy a Datsun roadster first.
If you want an example why there are no logics to classic car prices, someone just paid 0.5M on a '911' number plate. To me some people are so hung up by rarity, something rare does not necessary means it is great.