I prefer Ian's Secure Knot. I've been using this for 2-3 years on my shoes.
The knot doesn't come out, even with leather thong-type laces. Yet a single tug on the end releases the whole knot (unlike traditional "double knots").
>>CWuest+(OP)
It also keeps the fat, slippery laces on my hiking shoes securely tied. The only bad thing is that if you try to yank it undone and the single end has made its way through the loop, you may have a mess of untangling to do.