I almost always do a true bias binding. I also almost always do a striped bias binding, the only time I don't is if I can't find a suitable stripe. I use Shelley Rodgers method,
http://piraterodgers.com/tutorials/cbt/index.htm
The only time I use straight of grain binding is for mini quilts, whether it's crosswise or lengthwise depends on how big the piece of fabric is.
And I never press my binding in half before I sew it to the quilt; saves time and my bindings are easier to sew as well as looking better.
Cari