90% of the people in this forum will tell you that both are crap and that you better stay in your country.
But, I have friends on both airlines and they seem to be very happy, I think it all depends on where are you comming from.
My friends on Etihad are flying A320 and others A330, they got a nice apartment and their wifes and kids are happy, I have an other one that lives in Dubai.
The ones in Qatar are Singles so I dont know a lot about living in Doha with kids.
Hopefully you will find someone in here that will wive you a real comparison between them apart from saying bad thing about them.