I use Evernote to run my GTD processes, and have done so for the past 10 years. Without the ability to sort by tags, it is pretty much useless to me. I tag based on priority, without due/reminder dates, and sort these stacks daily/weekly/monthly. I use a search to present my daily p1 thru p3 list, and sort by tag so I can easily see the p1's then p2's then p3's in order.
I have a ton of stuff in Evernote, and love the tool, but if I can't find a way to sort by tags, I will have to find something else that can do both the helpful tagged storage and the GTD support.