Is there a more beautiful song than "Ar hyd y nos"? Also love "take me home", "hiraeth", "cwm rhondda", "tydi a roddaist", "hwiangerdd mair", "aberystwyth", "ti a dy ddoniau" just to name a few. Surely no Welsh night is complete without "men of harlech" and "mae hen wald fy nhadau". I would also include the great pub and rugby standard "Hymns and arias".