I greatly prefer
William to
Liam.
William is a wonderful, classic name, and
Liam, well, in my opinion sounds stuck-up, incomplete, and above all just plain unpleasant to the ears.
William Oliver sounds great, whereas
Liam Oliver makes me cringe (as
Liam tends to do to any combo).
I could go on and on, but frankly, in a short sentence its basically this: Think of all positives and put it under
William - think of all negatives and put it under
Liam. I cant think of anything Positive about
Liam nor can I think of anything negative about
William.