EuroFPL.eu
we use it at work. Flight plan automatically fully validated before submission along with direct emails for updates/delays/cancels. Allows a few free plans a month. Also automatically gets briefing pack for your route.
afpex is totally rubbish for most people:
a. It needs java usually on a pc (So no mobile access)
b. It’s a pig to access on business IT
c. It assumes huge amounts of obscure knowledge
d. It doesn’t integrate with flight planning tools
e. It rapidly becomes hideously expensive if you use for any commercial purpose.