I didn't care for the voices in Keepsake, but the game was so good otherwise that it's still one of my favorites.
Tony Tough is a game I've yet to finish, and Tony's voice was one of the main reasons why not.
I think I'd rather the girl in Tunguska had a phony German accent instead of the Californy girl accent she did have. I'm kind of sick of those Californy girl accents in games where they don't belong. Of course a genuine German accent would have been better. I didn't mind her high-pitched voice as much as her accent. I've known older women with high-pitched voices like that, but they didn't talk like Californy girls.
And speaking of annoying voices, let's not forget Samuel in Black Mirror. There were plenty of complaints about his voice at the time the game came out, but people tend to forget.