Dougal (if pronounced DOO-gal) sounds rather childish to me; like 'doodle'. I would only use on a pet.
Cool meaning though.
Oisín is better in comparison.
Niamh (that spelling in particular) is rather pretty too.
~☆October Song Recommendation☆~
Lucy Rose - "Shiver":
https://tinyurl.com/y3cx9f4v