I feel like these types of signatures aren't unique anymore since it seems like everyone is making them.. so your best bet is to improve a bit on your skills so you can stand out. Try a new shape, a new type of background.. but those pixel backgrounds IMO are too common.
Another thing, people won't want signatures that meet the exact limit, nor anywhere near it. If you haven't noticed, people are using tables to split their signatures to make the best of the space provided. You may want to experiment with many sizes, too. Especially for examples; that background might not be as pixelated if it was with a smaller sized canvas.