All three pictures you've posted are converted to jpeg, not sure but I think this kinda ruins the comparison don't you think? It now seems the middle jpeg does the best job, but perhaps that because it's a jpeg already and doesn't get converted twice? Just a thought .. Jpeg support would be nice for other reasons too, like for example no need anymore to batch convert textures found on the internet. They are mostly jpg's, only some are tga. Off course when things start to get serious everyone should make their own textures, but it would be somewhat of an advantage,

Cheers