Depends on where I'm going, what kind of a weather it is... stuff like that. But more often than not, i'd choose my vans... =) They're the most comfortable shoes I've ever had + sandals seem to fall off my feel a lot (difficult to walk in sometimes - strappy, don't adhere to the foot well enough... it can be awkward)
I love my sneakers. I went on an adventure through South-East Asia and only packed my Chuck Taylors. Only to find myself wearing flip-flops day and night. It think it really depends on where you're going with you're feet.
Sneakers. I love it like anything. If I wear heels or sandals I tend to twist my ankle I don't know why. And if I wear sneakers I can run around the whole day. And it's way more comfortable for me. I'm obsessed with Puma, Reebok, Nike and Adidas. And I wear flip flops only at home or when I'm super tired.