~ほうがいいんじゃないかな とはどういう意味ですか?

質問を翻訳

~ほうがいいんじゃないかな。
In this case, it is used to recommend something.
But it isn't asserted.
For example, it means
I wonder if red is better than red.
Or I feel like red is better than blue.

Ob the other hand, 赤より青のほうがいいですよ。
It is asserted that red is better than blue.