I have looked at them.
Here's my analysis. I apologize ahead of time if I speak out of line or do not provide enough input.
First signature:
I find the 'ink blots' or 'black splashes of paint' to be well done. Impeccable. Not too much, but enough to keep it interesting.
The name would look better if it had a slight outline. The shadows are fine and the position/angle is good too. I just find that the name blends a bit with the background, so having a slightly darker outline will help.
For the main subject, the character sets the tone well. The 'wing' and even the sword looks more captivating than the person. If that is what you're going for, then it's a success.
If you wanted the person to stick out more, maybe enlarge it or a glow effect. Although, I'm sure you know best about what to do to make things stick out more.
Overall, this one I find more appealing than the second one.
Second signature:
Unlike the first one, the main subject is definitely more at focus.
Grabs the attention right away.
The position of the black birds are used brilliantly and not too heavily. How one of the birds is 'sitting' on top of the letter 'i' is well done.
As I mentioned, the subject is the main focus. Therefore, the name on the background doesn't stick out as much. It's just decent.
The red isn't too bright, but captures the mood and allows the signature to speak for itself.
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Now, why do I like the first one.
The main reason is because it appears more like 'art'.
Those fine blue-green lines and how simple in yet subtle it feels.
I think of it as less 'in your face' unlike the second one. Instead, the colors and typography convey the initial mood and message.
The second signature is good in its own right. Very bold and would make anyone look at it more than twice.
I just find the first one... more aesthetically pleasing.
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Hope it helps.
Thank you for sharing~