I don't think any character embodies 'absolute good' in Lord of the Rings, for a couple of reasons.
Firstly, as Tolkien created Eru as creator of his secondary world, and as an Omnipotent god figure, it wouldn't be possible for any other character to be 'better' than Eru in terms of being 'absolute good'. If say Gandalf was an ambodiment of 'absolute good' then this would make him better than Eru and that wouldn't sit well with the existence of Eru.
Secondly, Tolkien states that he does not believe that 'absolute Evil' existed in his creation. While that does not exclude 'absolute Good' (unless you think it is Dualistic or something like that) it does mean that Tolkien created a Creator who could/would allow 'evil' to exist; in the Silmarillion it states that the works of Morgoth ultimately only served to make Eru's works better. What I'm trying to say is that even Eru is not 'absolute Good', he is simply Eru and beyond all of that, beyond the ken of mere Men and Elves and even Valar.
Thirdly, as we've discussed many times, our 'heroes' all have flaws. None of them are 'perfect' - even Gandalf is a grumpy old pipe-smoking hippy (
), Frodo has his weakness, Tom Bombadil does not 'get involved' but hangs out in his woods singing trippy songs...etc...Lord of the Rings is a tale where there are no perfect saintly or muscle-bound 'heroes', but lots of very interesting people with failings just like us, doing their best.