[Z]

Dublin to Holyhead looks like it would make the most money but I think a direct link between Northern Ireland and Scotland would be brilliant, so many Northern Irish people live on the west coast of Scotland. Campbeltown is about 3 hours away from Glasgow but it's the shortest link and therefore cheapest; Stranraer is less remote but I don't know if it's any closer in terms of driving time. Rosslare-Fishguard seems a bit obscure but it'd be good for the south of the Republic to have a link to the south of Wales, easier to get to London by driving.