Out of all the people I've met, I haven't met many people that are good natured like she is.
「出会ってきた中で彼女みたいな性格いい人あまり出会った事無い」というのは Out of all the people I've met, I haven't met many people that are good natured like she is と表現できます。
出会ってきた中で out of all the people I have met
彼女みたいな like her
性格いい人 good natured person/person with a good character/person with a good disposition
あまり出会った事無い I haven't met many
参考になれば幸いです。