It's dependent on your use case, but the three examples you've listed here all have a slightly different approach to the market. Stitch (as mentioned in a comment below) is SaaS only. Pipelinewise is open source but as far as I know have no plans to build a company around it. With Meltano, we're aiming to grow the project and community and eventually build a business around it in a similar manner to what GitLab has done. Our docs[0] have more information about our current focus and roadmap if you're curious.
Stich is SaaS only. That by nature makes it suitable for some uses, and unsuitable for others (like when you have a provision that your data can't leave your network or when you are in a company where adding a new vendor isn't a quick process.
Meltano and Pipelinewise are open source projects that someone built for themselves but are sharing. You can just start playing with it and change the code or whatever, but there's no support to pay for.
For example where I'm standing the best one would be "Stitch I can self-host for free for a PoC and then eventually engage vendor about a support contract while still self-hosting it for security reasons" but there doesn't seem to be anything like it.
Since Stitch, Meltano and Pipelinewise all use Singer.io taps and targets under the hood, I wonder if there's any reason to choose one over the other?