Ideally barefoot as nature intended.
But life and babies conspire against you - my DD started walking in winter in a house with no central heating and slippery wooden floors. And she thinks it is hilarious to pull off her socks and hide them. An investment in a pare of Robeez (on sale) saved me a fortune in socks.
She is now in proper shoes but has spent the last two days barefoot running around in the sunshine.