SkyDemon is very easy and quick to use. I can plan a route in less than a minute and it will get winds aloft, NOTAMs etc immediately so that I can choose to adjust the route.
I don't file flightplans so haven't activated this feature, but all you do is set up templates for the aircraft/pilot combinations and the form is automatically filled in. I believe the charge is about £1 for each filing.
One feature I like is the ability to operate on multiple platforms. I can create my route on my PC, upload it to the cloud, then download to my Nexus 7 and also download as a backup to my iPhone.
The maps for all of Europe and NA are included in the price.
You can try it for 30 days as a free trial. I find it works faultlessly and reduces an hour of flight planning to a minute or two.