In my view, as customer and user, Cloanto is the better choice as Mike has stated he will open the OS as much as possible, including open sourcing as much of it as possible...
Which may be "not possible at all", a possibility you may have seem to forgotten. The question here is in how far the contributions can be opened as it requires a license change, and potentially renegotiations, potentially with parties that you can no longer reach. By that I not only mean "our contributions" or "Os 4 contributions", but the trouble goes back to CBM times, and what CBM negotiated, and which licenses they had.
So, just to give you some ideas: The dos.library is not only Tripos and CBM code, it is also ARP code. Did CBM have licences to put out the source in the wild? Or only for their internal Os development purpose? What about ARexx, which is a third-party contribution? What about CrossDos?
We already found out that the narrator.device didn't have a source code license at all, but only a binary license, so its sources are completely unacessible unless someone is willing to pay off SoftVoice, which is exactly the reason why it is no longer included in any Os version beyond 2.04. Chances are that its inclusion in 2.04 was not even covered by a valid license at all and only the original unextended version from 1.2 times was really ok.
Reaction is something Hyperion recently acquired. Whether the license they paid for allows opening the source I do not know, but I'll bet that Hyperion is not willing to give that away for nothing after having paid for it.
So please don't believe in the shiny rainbow Cloanto is willing to promise. That is nothing but politics. Reality is much more cruel. If you want something open, without entanglement of third party rights, your best bet is AROS.