Its a difficult question to answer and each home location seems to differ from our experience .
We left Eircom 2 years ago and signed to BT - we left BT a year ago and signed back to Eircom - left Eircom a week ago and signed to 3G
Had a problem with 3g wireless range in our house . After much help from technical support , it was agreed that our large old chimney was causing a problem with signal between upstairs and downstairs .
In our case , a wireless broadband is not sufficient , and we would not survive without a cable connection . ( the landline is essential )
Therefore , we are now back with Eircom again , and cannot fault their 100 %service .
In our neck of the woods , BT/Vodafone also have a great reputation .