What they share
Both are Hebrew biblical names with strong, warm meanings. Both have aged without feeling dated. Both pair well with classic English middle names.
Pick Ethan if…
Pick Ethan if you want the softer, more modern sound. Ethan means 'strong, enduring' and has a calm adult quality. It has no obvious nickname, which some parents appreciate.
Pick Isaac if…
Pick Isaac if you want the more distinctive biblical choice. Isaac means 'he will laugh' (a reference to Sarah's laughter in Genesis). It carries more scriptural weight and has Izzy as a lovely childhood short form.