These books were the most interesting ones I read this year.
These were some of the best books I read all year.
ーThese books were the most interesting ones I read this year.
「これらの本は今年読んだ本の中で一番面白かった本たちです」
the most interesting ones (books) で「一番面白かった本たち」と言えます。
ーThese were some of the best books I read all year.
「これらは今年読んだ本の中で一番面白かった本のいくつかです」
some of the best books で「一番面白かった本の何冊か」と言えます。
ご参考まで！
カナダ 
