I use either the Cabrinha surf straps like these
www.kitepower.com.au/collections/kitesurfing/products/cabrinha-surf-strap?variant=29843878660Or the Dakine "Slim" surf straps like these
http://eu.dakine.com/w/windsurf/footstrapsBecause you can stand on them, they are lightweight, once adjusted to your foot they do not stretch and they are comfy.
I have a pair of the NSI on a Delta board, they are comfy too just a bit bulkier, and you will have trouble standing on them. I need to be able to stand on them because I switch, and it just helps when you move your feet if you can stand anywhere.