The 'best deal' depends on how you plan to use your phone. Lots of international calls? Lots of data? Whatsapping rather than texting?
My suggestion would be something south of Northern Cross near Malahide Rd (I'd suggest on but I think that may not be the 'quiet' you are looking for). You are talking 'north side' of Dublin here which as a reputation as being rough. You could consider Artane or Killester (the latter having the advantage of putting you on the DART/metropolitan railway) but this area is not really 'studio' area. There are some nice new apartments in Balmayne and Clongriffin is nice (and probably walkable to Northern Cross and good access to the city centre but again, not really studios.
Ultimately my suggestion would be to set yourself up in a hostel for a few days and then look around. Perhaps talk to people you are studying or working with about what they think is a good place to live relative to work, your requirements and so on.
My opinion would be different to lenny. I've done this kind of thing heaps of times and normally give myself a base for a few weeks before deciding where I want to live.