1 and 2 look very close to me, with 1 seeming slightly better. What’s your opinion?
My opinion: 1 and 2 look “crisper” than the others, but that’s because the picture has no sharpening applied. In fact, 1 and 2 have (according to my eye, I might be totally off here – but it would be nice to know 
some amount of false detail that is typical of IGV and/or LMMSE demosaicing, which were designed for noisy images. Here’s an example of RCD vs IGV (without sharpening):
I agree that in general the differences are minor, but it’s good to have a choice for dealing with more difficult situations…
I think you’re going to need shots of a resolution-sort of target. Something white, with lines…
depends on what you are interested in… there are clearly visible artifacts in one of the pictures above, if you know where to look. E.g.:
I find that capture sharpening can make these artifacts clearer. In fact, in one PlayRaw, I had to turn off CS because it was revealing them (maze patterns) in an unpleasant way.
I thought 1 and 2 were better because I didn’t see as much the colors atop the tower:
1
6
Now I am thinking they really are those colors. I am not familiar with the tools used above to find the differences; I am just eyeballing the things that stand out to me.
Alberto, you’re almost fully correct!
1 = IGV
2 = LMMSE
3 = 7 = RCD
4 = Fast
5 = AMaZE
6 = DCB
I would have gotten IGV and LMMSE wrong because I don’t use them or know when to use one over the other.