Urgent smart question need smart and clear answer : f40 or f31?

50% make f31 the winner because it's better in low light (f31 iso 1600=iso 800 f40),and 50% make f40 the winner because it's better outdoor and better colors,is that information true??Please give clear answer that dont make me more hesitation.

The F31 does do better in low light, and the F20 likely does take better daytime outdoor pictures. One reason is that the F20 has the "noise reduction" tuned down from what it was in the F30/31/20. It also has a third more megapixels crammed onto an only slighter larger sensor. The result is noisier pictures at higher ISO (less light), but a bit more detail at low ISO (bright daylight), where noise is not much of a problem to begin with.

If you're still trying to choose between one or the other, most people I have heard from who have used both decided to stick with the F31.

You could also wait a number of months, if you're in no hurry at all, to see what will directly replace the F31 (the F40 being the replacement for the F20). Good luck.