True, the FLTPLN comparison page is nice. Other than that, though, I'd put Foreflight up against FLTPLN any day of the week. Once you've got your profiles set up, you can get accuracy with Foreflight just as good as that offered by FLTPLN. You can add preferred routes easily. You can visually assess the various DPs an STARS against where you are going. I find that much easier than having to page through each DP or STAR on paper to figure out which ones make sense for my overall trip, and then having to go back to the computer to enter it into the flight plan. At just a quick glance I see all the DPs, for instance and instantly know which one is most appropriate. I can also see NOTAMs associated with each procedure on the procedure which allows me instantly to know if the procedure will even work or not. That way I don't file, then read the NOTAMs, then have to go back and change the filed flight plan.
I think, as with many things, it boils down to what one is familiar with and comfortable using. They are both good tools.
But....... that interface!!! Aiiiighhh. Drives me batty.