I have done all of those methods for straightening the grain. I am also fond of tearing.
However, for quilting, I find it is more important to pay attention to the fold, and be sure that you have lined up one line on your ruler for that. That way, when you cut across the grain, you will have a straight cut, and not a 'V' when you open out the fabric.
I use bias cuts frequently and never have a problem. I think it is more important to cut accurately than for the fabric to be perfectly on grain.