这种问题，没有上下文，问了也是白问。

难道说真有一个词比另一个词不顾语体，不管上下文而绝对要亮或高级的么？

稍加想想，就知道这种词不可能存在，如果有，那其它的词就不存在了。

比如，据说下面的是2018年高考英语范文, 这里有2个“应该”:

Dear Terry,

How are you doing? In your last letter, you asked me about being a guest to a Chinese friend 's home. Now, I am writing to inform you of some relevant details.

To begin with, according to our tradition, you are supposed to arrive early, so that you can help the family prepare the dinner, which is not only meaningful but also interesting. Besides, you'd better bring some gifts, such as a book or a Chinese knot. What's more, when you are enjoying the meal, you need to avoid making noises while chewing food.

Hopefully, these suggestions would be helpful for you. I have the confidence that you will have a great time. I am looking forward to your good news.

Best wishes!

Yours,

LiHua

可是，两个“应该”都用错了。（这范文还有其它错误）

are supposed to --- 用于按时到校、生病得去看医生这种“应该”才对；

本文Terry会觉得Lihua莫名其妙，你们的传统文化会有这样去“束缚”人家么？

you'd better --- 用于语义可以施加影响给对方的这种“应该”才对。

本文Terry 又奇怪了，你们中国人家庭这么死要的么？不带礼物真不行？

以上两处, 正确的应该是“it's better to do”, 或者“may as well”

It's high time 表“应该”也许是个不错的选择，但意思也同样得需弄清楚。

   能真正用好这些表达就够了。