Tone, convenience and interface preferences are pretty subjective and personal taste, so go for what makes you happy and covers your needs.
Pricing is about facts, offer/demand.
Kemper retail price positioning ($USD), since I recall, has always been below Fractal’s.
Now, with the Stage, you get a full Remote functionality+full Profiler features with same processing power as the head unit and extra I/Os for retail price $1.7K. ($1.8K head or rack version without Remote) vs a new AXE III $2k. (without foot controller). Maybe with the FM3 you will get a full featured AXE III for $1K. with less processing power, less I/O and less foot switches to start with. It is not apples to apples, though.
Right now, according to Reverb’s price guide, an average of used and new actual selling street prices, Kemper head street prices have dropped by 13%, from average $1.5K in 2017 to $1.3K. 2019. While AXE III head prices dropped by 35% from average $2.7K in 2018 to $2K. in 2019. During the same period Kemper rack version street prices dropped by 10% from average $1.55K in 2018 to $1.4K 4Q2019.
Personally, I don’t think about resale value when I buy music gear, because I am not in the trading business, I prefer to enjoy gear that last as long as possible, like a great vintage guitar.
The Kemper OS is older than new AXE III for sure, but not older in what it delivers. I appreciate that Kemper’s business model has not factored planned obsolescence by design and we enjoy the same ”older” unit with new features every year. I’ve lost the count of AXE iterations, a great device, too, but hope this time they keep this new version longer than the previous ones, it is a great unit for sure.