Are both machines at the same dealer or different dealers? If different, do consider the dealer support aspect of the machine if the machines feel similar to you.
I'm not directly familiar with either machine, and while not scientific, a Google search turns up lots and lots of actual quilter discussions on the Crescendo and nothing but marketing and "influencer" YouTube videos on the Viking. The latter are a particular turn-off to me, as nearly all these "influencers" receive compensation related to putting videos out there. It's actually their job to produce these things yet appear to be "independently helpful".
That said, both are quite pricey machines, and if your primary goal is to learn FMQ, you might want to consider something at a lower price point. For FMQ, more bells and whistles aren't necessary; FMQ is essentially straight stitch.
Last edited by mkc; 12-18-2019 at 06:13 AM.