Issho (Fujitora) is my favourite character of One Piece. He didn't appear often, but when he did, it was fantastic. His thoughtful way of being, the way he acts and speaks and his wisdom make him my absolute favourite. Oda did a fantastic job on his character design. The character is so deep, full of meaning and symbolism. He sees everything, because he is blind. His DF is the one of the strongest forces of nature (gravity), while his character represents the opposite, the state of not being attached with the ego (dharma). Like the other admirals, his character represents the opposite of their representive power (Borsalino = Lazy, but lightning speed / Kuzan is warm-hearthed, while his power is ice cold, etc.)
I also really like Issho's theme soundtrack and VA in the anime. Besides Fujitora, I also like Shirohige, Shanks and Rayleigh.