I have a Helix, a Kemper and the Axe FX II.
They all do different jobs to varying degrees of success.
The Helix is a great device when I have no time to set up and just need to plug in and go.
I resisted it for a long time (although I was an early adopter of the Native plugin) but it is an excellent device.
The Kemper I mostly use for profiling amps- its modelling sounds better than anything else I have.
The Axe FX II I use in the studio- I've owned it the longest and it does some things that I cannot do with other boxes.
I gigged the Helix last night, direct into the PA and it sounded fine.
I still prefer tube amps, if the gig allows it.