Lachlan looked the best to me out of those choices.
South Africa had a crack horse-jumping rider named Lachlan MacLachlan. Sadly he died not too long ago, at a young age.
But Andrew is a solidly Scots name too, for all that it is of Greek origin (it means “manly”).
And Alexander (popular in Scotland since the time of Malcolm Canmore and his queen, St Margaret) is of Macedonian origin. The Gaelic form is Alasdair.
Regards,
Mike