What makes him so unlikeable to you, that's what I'm curious about. Tobirama has a nice design, sure, but I get the feeling that most people who refuse to even give Hiruzen a chance dislike him generally because of his old age.
In all honesty, Naruto is the only manga I've read where the old characters are truly handicapped. Hiruzen had insanely low stamina in his old age, and Onoki has back issues. But in most of the mainstream manga, anyway, the older characters tend to be one of if not the strongest in the series. Yamamoto from Bleach; Makarov from Fairy Tail; Rayleigh, Garp, Whitebeard, and Sengoku from One Piece; Netero from Hunter x Hunter; and despite mainly being comic relief, Roshi from DBZ is ridiculously powerful, though definitely not the strongest.
That said, I understand that people don't want to acknowledge Hiruzen being a strong character unless they actually see something worth being impressed by; and the fact that Kishi kind of trolls him, but logically he should at least be worthy of being called Hokage if he got it in the first place. And I still have trouble understanding why people call him fodder.