Ciel's route Ciel pisses me off, but her route provides the most information on Roa out of any route, so its a recommended read even for a Ciel hater.
Besides, anyone that reads visual novels should know that the quality of the route is not directly proportionate to how likable the heroine of that route is.
Hisui = fairly likable, but dulls in comparison to the other Tsukihime girls
Hisui's route = awesome
You = best Ever 17 girl
You's route = worst route in the game
...Though it is fucking awkward choosing the pro-Ciel options when they give you a choice between siding with either her or Arcueid, especially since she kept pissing me off in her route.