I had never heard of Shauna Burns, but will have to check her out. I've often thought that Susan McKeown had one of the cleanest, clear Irish voices I've ever heard! Very beautiful voice, although it might be low for some, depending on if you like low or high voices. I find high voices pleasant but they seem to "get old" fast. A voice with a wide range usually keeps your interest more. Celtic music as a whole can get tiresome quickly, so it is nice to switch between different voices and styles.