Text to text comparison, just like I learned back in elementary school, and forgot for 7 years.
Reborn's characters are often very unique, but they do have similarities to other fictional characters. Let's use this dumb thread to name a few.
I've mentioned that Lin is Sephiroth, mainly because they are overpowered, and seem like villains who have everything planned out, although in Sephiroth's case, this was mainly because of the JENOVA cells within Cloud. This comparison is extremely weak, and I feel Lin is more Aizen than Sephiroth, mainly because Aizen literally plotted Ichigo's entire rise to power. This is entirely based on speculations that I've seen users make in the past, so, this isn't really a confirmation. Ame could write in a plot twist in which Lin doesn't actually know what she's doing, and she just acts like it. The problem is that we don't really know much about Lin.
Saphira is Afro Samurai. Simple comparison. They are both extremely murderous, and they seek revenge for wrongdoing done to their family members, Saphira for the electroconvulsive "therapy" (torture) done to her sisters, and Afro for the death of his father.
Conversely, I don't think Sigmund represents Justice. Sigmund seems like a guy who has an army backing him up and uses "the law" as an excuse to continue his wrongdoing. Justice works alone, doesn't care about the law because there is none, and is so powerful that he doesn't need an army.
Taka is Jetstream Sam. That's two Samurai i've made comparisons to. Taka has some degree of Loyalty to Team Meteor, the same way that Sam has some degree of loyalty to the Winds of Destruction and Senator Armstrong. Neither are really "bad" guys, and you end up considering them more Rivals than enemies. They even help you at times. Taka stopped Amaria from dying (Although in the Reshiram Path, this could be interpreted as him unintentionally almost drowning you), and even assists you in the desert. Jetstream Sam passed on his Murasama blade so that Raiden could defeat Armstrong.
And That's all I have for now... These comparisons are really just surface level looks. The Circumstances behind each action are different, and the context is also different for each action.
I really shouldn't become a story writer. I'd make my own characters way too similar.