I assign my tasks an importance on a scale of 1-5, and an urgency on a scale of 1-5. One can also use the four quadrants of 7 habits- urgent important up to not urgent not important. One can also assign a metric of the consequence, that is how consequential will this task be over the long term. All of these helps one sort and set priority on the tasks other than a knee jerk emotional setting. These metrics tend to evolve and also combined in different ways. I find these methods absolutely critical in deciding what should be done each day. I can find no app that fires this well. This is an opportunity.