My dream would be seamless interoperation between all these tools. Would also mean better 'competition', easier to convince people to try them, avoiding lock-in in one tool, etc etc.
For some tools it's already possible to interoperate -- for them would be nice to have summaries on what are the caveats (e.g. would the tool format my whole note base? would it break any special syntax imposed by the other tool? etc etc)