Disclosure up front... I'm a huge Jepp fan. I've played with all of the apps and I have to say the functionality of the Jepp platform is so much more powerful than either. Jepp doesn't stitch .pdf charts. Theirs are seamlessly digitally created on the screen out of the raw data. That's why their charts customize what they show as you zoom in/out and update themselves based on NOTAMs and give you pop-up notes that comes from AP/GP/etc. Their new airfield diagrams actually show areas that are NOTAMed closed...f-ing cool when you're at a busy unfamiliar place. And, Jepp can tie together their other apps/products together so they talk to each other...TOLD performance data, mission info, insert your own charts/info, build your own routes, etc. Damn cool stuff that let's us use the EFB for more than an e-reader!
BTW, I heard that Jepp and ForeFlight are coming out with a merged app that blends the best of their platforms and Jepp's global data. That ends the debate.
But the chances the big boys will ever let that capability get into the cockpit...