I like Gráinne, it's very romantic. It makes me think of old castle on a cliff near the sea, with the storm coming and waves crashing against the rocks, wind howling and beautiful woman looking out of the window, waiting for something.
Grania I like too, but not as much as Gráinne.
Grania is more practical - no castles and storms for her. She lives in a city, likes to bake and has a long wheat-coloured hair she always braids.