So after being an owner of a Kemper for the last few years I recently decided to give the Helix a try. While attempting to offload said Kemper I got offered a straight trade for an Axe FX 2 (oops, though I have owned and gigged one ages ago.) so here's a brief overview of my thoughts. Kemper - Arguably the best modelling of the lot. Certainly sounds damn close when profiling a real amp. Easy to use interface, easy to tweak and set up patches. Doesn't play very nicely with valve amps, if you're planning to use it as a preamp this is the weakest of the lot, even with preamp profiles. Effects are hit and miss, modulation is pretty good, delay is great sounding but very limited. Drives are poor. Axe Fx 2 - Also sounds great for amp tones. Definitely has its own thing going, is darker and more polished overall which isn't a good or bad thing, personal preference. Sounds great with valve amps, especially as a preamp. If you want a preamp/power amp setup this is the one. Effects are amazing, BUT... They can be a faff. Simple effects are easy enough but more complicated stuff requires creative use of various different block and routing which arguably makes it the most powerful and also the most awkward. The interface is horrific, and I know how to use it just fine. It's just a pain and unintuitive, I can see how it can be learnt but after using the other two... Christ it's bad. Axe edit sort of makes up for this but it's not ideal. Helix - So far I'm still of the opinion that the modelling is the weakest of the lot. It certainly improves with IR's added, stock cabs are not my thing at all. A bonus is it somehow sounds rawer and more in your face than the others which I do like. Especially noticeable on the Recto model. Interface is amazing, I didn't think it would matter so much but it really is a joy to use and a snip if you need to change anything mid gig. Effects are great as well. Less complex than the Axe FX but great I their own way. More akin to a nice collection of stomp boxes rather than a studio rack processer. Delays especially are impressive, the analogue stuff is the best out of all three units. It works amazingly well with an amp too, not so great as a preamp but as a pedalboard it's the best multi effects I've ever heard, properly transparent and the drives are great. Lag between presets is awful, making it pretty much unusable in this way for me. You can work around it by having different tones in one patch but still, it's not ideal. There you go, any other questions regarding the units please ask. Oh, and any flamers / fan boys etc please give it a rest before you even start. It's about making music, not about who's got the best toy in the playground.