Translation:Which tie would you like?
「いい」 does means "good" but in some contexts it seems to me that it's closer to "like" than to "good" or "okay".
When asking for a choice, it doesn't just means than it's okay or good enough. It means that you like it, it's the one you want.
You can also use いい for a person you like (non-romantically) or a type of food you like. 「ラーメンがいいです。」 doesn't just means "ramen is good I guess", it means "I like ramen". And using "good" to describe a person in English would almost be offensive (what? I'm just good, that's all?), in Japanese it means you like that person.
Also, I am not 100% sure, don't quote me on this, but... I "think" that, が renforces the "I like" meaning of 「いい」 and は the "it's good" meaning of 「いい」. (Edit, more on this: )
「あの先生がいいです。」(I like that teacher)
「あの先生はいいですね。」(that teacher is good, don't you think?)
If you want something, weaker than 「 いい」 I guess you could use 「大丈夫」, or use は I guess.
Actually I found more information on this: https://hinative.com/fr-FR/questions/9328567#answer-23425289 and https://japanese.stackexchange.com/a/34488
So based on this reply from a native, this is how you would respond to the question "which tie do you like?".
「そのネクタイがいいです。」 I like/I prefer that tie.
「そのネクタイはいいです。」That tie is good.
「そのネクタイでいいです。」That tie is fine/will do.
「そのネクタイばいいです。」That tie would be better.
Also explains the anime title 「妹さえいればいい」 (a sister is all you need)
Don't you love/hate particles?