I keep hearing about the Saw Doctors, I got to check them out.
Seven Nations an ETH are the standards with Rathkiltair, Great big Sea and the Glengarry Bhoys, always a must see. Dropkicks and Flogging Molly are a few peoples faves here. The Pogues well what can I say.
There have been some decent lists made of a lot of good bands.
It's all about individual taste.

Kilted Stuart