Soapbox is likely the best available, but was pretty disappointed in it during my use of it in Legion. After hanging out in the discord for the new product, I think it has/will have the same issues.
Basically if you don't play a feral druid or shadowpriest, I wouldn't purchase. The mass majority of the rotations are outdated and underperforming, with no devs even working on them for the entirety of legion. This has gone on for months multiple times with Soapbox Rotations. If you happen to play a spec that has one of the devs who also plays (empirically feral/shadow priest) sure it's awesome enjoy the parses, but if not I would wait and see how the new product turns out.