The 625 will almost certainly be the better gun for increasing value and collectibility. The Shield has to me, a certain merit for carrying. As I have said before with relatively few rounds through the Shield; it felt to me like a very long term ,familiar pistol. Around here the .40 Shields seem to be more common (and perhaps slightly less desirable) than the 9mm versions.
I never talked to anyone who had to fire their gun who said "I wished I had the smaller gun and fewer rounds with me" Just because you find a hundred people who agree with you on the internet does not mean you're right.