It's great to hear that you are planning another trip to Ireland. I'll start by saying that you can't go wrong with either the Dublin or Cork areas. When it comes to sightseeing, good food and drink, and music, both areas have plenty to offer.
I would like to link some pages that may help you to make up your mind better. When it comes to the Dublin area, check out this link on how to spend 72 hours
in Dublin City. Here's another link that highlights the top attractions
in the city. Outside of the city, County Dublin also boasts many wonderful coastal towns
and villages that I'm sure you would enjoy exploring.
County Cork is Ireland's largest county and home to the third-largest city on the island. Here's an interesting link with the Top 9 attractions
to see in Cork City. Part of the Wild Atlantic Way
is in County Cork and there are many wonderful towns and villages to explore, including Cobh, Kinsale, and Blarney. Cork also has a well-earned reputation for great food, as you can see here
Wherever you go in Ireland, good craic and music will be easily found. The decision on where to travel is yours, but I will say either option would be a winner!