Akari: Okami is pure love <3 Anyway, I think it's a pretty good. Maybe it needs lighter colours in the background to match with the render and to add contrast to the dark purple. I like the sparkle-y, star effects you used to make it look more, er, celestial-y. The render itself looks sharpened and a bit too over contrasted, though. The text in the corner looks quite isolated, and it needs to blend together with the rest of the banner a bit more. Perhaps bring it closer to the render, and make it go together with everything else somehow.
Kouyuu: Nudge the render up a bit. I don't like how it gets cuts off at the bottom of his chin. That's an interesting choice of colour, though it does work. Nice light source behind his hand/sword. Though sharpen up his face, since it all looks too blurry for me. Also, shift around the text. I don't like the positioning, and how all the words just seem to float there in the banner. And the underlined x's get a no D: Maybe mess around with the colours as well, since there seems to be too much contrast between the darker render compared to the text and the background.
Animadversion: Those are pretty cool~ I like the use of the mosaic effect for the first one. Although it does slightly mess up with the diagonal flow of the banner x___o It still looks nice, since it adds colour to an otherwise black and white background. I like the starry effects in the background, as well, it sort of adds depth to the banner. The render seems to be a bit too bright overall, though, so it looks like she's glowing or something. The box around the text is kind of distracting as well. It makes the text look too... neat, I guess.
I absolutely love the concept of the second one. It's simple, but I really like it. The text fits nicely with the banner, and the simplicity of the effects means it's easy to see where I'm supposed to look at. But maybe bring out the wings a bit by increasing the brightness of the lighting, just to make the banner less empty around the edges.
Hazuki: Eheh, I was never one to like animation in banners. But it does look alright in this one. I don't like how the text is centered, and how the left side seems to be emptier than the right side. The scan lines seem to be too strong, too. Actual effects, like sparkles as Akari has said, would have looked better than scan lines, but, er, yeah o___o
CheesePeow: I don't like how the edges of the render are all blurred. Using mainly white for the background makes it looks sort of empty. It needs more colours, and a lower brightness. You could have gone with a simpler text style as well. Usually, when it's small text, a simpler font is better. Well, in general, a simpler font is better xD And tidy up the effects. It seems to be all over the place, with the scan lines, then those wavy brushes and the smudging.