I think if I was renting I would look at a place close to work or close to where I really want to be - whether that's by the sea, close to the city centre, beside the mountains, beside family or wherever.
The difference between renting in very desirable areas such as Clontarf, Sandymount, Blackrock etc and places in west Dublin is not always that much (compared to the difference if you were buying in these places I mean).
Apart from that, I believe Ongar is nice. Bad traffic, hard to get places in schools, but there's new shops / restaurant / pub opened up nearby so for a singleton with no kids (who can work from home??) it could be perfect.