。
I've always preferred people with mysterious personalities.
Literal
I [topic-は] always strange [adjectival-な] personality [genitive-の] side [subject-が] liked [past-だった].
The structure [X]の方が好き ('the X side is liked') is the comparative way to express preference — 'I prefer X.' 不思議 here is closer to 'mysterious/intriguing' than literal 'strange.' The past tense だった ('was liked') with いつも ('always') gives a habitual/lifelong sense — 'I have always liked,' a state that persists into the present.