I really liked Sayonara My Alpha or Sayonara Alpha (i forget) the sumary is basically this omega tht was thought to be a alpha found his soulmate but his soulmate is in kindergarten or elementary school and yea im sure u can guess wat happens next, its also very fluffy
I can't say which one's best for your friend as it depends on individual. These're great & light read..
http://www.mangago.zone/read-manga/abarenbo_honey/
http://www.mangago.zone/read-manga/sayonara_alpha/
It's not easy to find omegaverse without rape so I'm sorry for not having much to recommend
http://www.mangago.zone/read-manga/kasegimasen_kara/
http://www.mangago.zone/read-manga/tadaima_okaeri/
Kashikomarimashita, Destiny. I absolutely love the second couple
Can someone recommend me an absolutely best omegaverse manga ever? Oh yes I need those pages of explanations as well because IM GOING TO RECOMMEND THIS PROJECT TO MY FRIEND HELL YES