If I had to choose... / If I had to pick...
Frame for giving a preference when asked to choose between options. Si tuviera que + infinitive = if I had to + infinitive. Uses the imperfect subjunctive.
If I had to choose, I'd go with the first option.
If I had to pick between the two, I'd choose the blue one.
—Which do you prefer? —If I had to choose, I'd say the second.