I haven't had a Kemper but I had a Helix (sold) and currently have an AX8.
I sold the Helix because the AX8 just sounds better out of the box. I bought an ownhammer impulse pack but even with those, the AX8 sounds better - especially after recent updates.
Don't get me wrong... the Helix is a bad mofo. In reality, the AX8 can't hold a candle to the features and ease of use of the Helix... but I just couldn't get it to sound as good as the AX8 and someone offered me what I felt was a good trade plus cash deal for it and he wanted it badly. An H9 MAX, H9 Core and $600. Off she went.
I have to admit, I paid WAY TOO MUCH for my AX8. It was an impulse buy when nobody could get them because they were backordered. I paid $1600. NO REGRETS. It's a USA model so I think I can get my money back later.
Here is where I think some people on this board will laugh at me
Over the last 2 weeks, I have been really digging this Line 6 DT25 head I got in a trade. It was updated so there are 40 amps in it right now but I started using it with my G System (in a rack) and I love it. If you have never tried one, you had better keep your mouth shut lol. These amps are killer, IMHO, and you can get them cheap as shit.