If you could only pick one, which one would it be?
この場合、次のような言い方ができます。
A: Either one is fine.
「どっちでもいいよ」
B: If you had to pick one, which one would you pick?
「1つ選ばないといけないとしたら、どっちを選ぶ?」=「どちらかと言うとどっちですか?」
または次のようにも言えます。
ーIf you could only pick one, which one would it be?
「1つしか選べないとしたら、どっちですか?」=「どちらかと言うとどっちですか?」
ご参考まで!
If you had to pick one, which one would you choose?
ご質問ありがとうございます。
・「If you had to pick one, which one would you choose?」
(意味) どちらかと言うとどっちですか?
<例文>If you had to pick one, which one would you choose?// Maybe the red one.
<訳>どちらかと言うとどっちですか?//多分赤い方かな。
参考になれば幸いです。