Apologies if this has already been suggested, but there is a simple method of implementing priorities in OF. I want priorities, but I do not need estimated time for actions. So I type a number from 1 to 5 into the estimated time field for each action. I can sort this field so that every 1 (high priority) comes to the top, while every 5 (low priority sinks to the bottom).

One advantage of this system is that, unlike iGTD, you don't have to apply a priority to every action. Any action without a priority drops to the bottom of the sorted list, where it can be reviewed and given a priority at the appropriate time.

It is irritating that OF automatically appends 'm' or 'minutes' after the number, but I can live with that.

In my experience, no action list software is perfect. That's because we all have different ways of working. I have tried iGTD, but the less-than-elegant interface and lack of recent upgrades made me move on. I was using Things for a short while, but missed being able to see a complete list of actions on one screen, and found the repeat option confusing. So I am back with OF and finding ways to make it do what I want, rather than the other way round.