i have both, axe fx and helix...helix is nice and has alot of potential (if line6 keeps on updating) but axe fx is far superior. it not only sounds better, but there is also alot alot more experience and thought behind. how you can control everthing, turn on and off stuff, scenes....etc etc etc...goes on and on and on. people who dont have axe fx or are not really familiar with it cant understand. its hard to explain and way easier to show.
the only better side of helix is. more in and outputs, mic input and the editing on the unit is way easier and more fun...my 2cents...
still i think i will keep helix for a while and see how it developes. (even though axe fx has still way more frequent updates. i dont know if line6 will ever be able to catch up).