I’m also very interested in this, and having trouble finding one that suits my liking.
The problem I’m seeing - and I’ve tried a few (OrangeTree, AmpleSound, RealLPC) - is that they are all built for MIDI input via a sequencer or MIDI controller, not MIDI generated automatically from notation.
As an example:
It’s very common for slides / hammer-ons / pull-offs to require overlapping MIDI. However, that’s not how Dorico renders the MIDI for a slurred passage.
If any Dorico experts can help with this type of issue, I’d love to know.
As for expression map - those aren’t too hard to generate and I’m happy to share what I come up with if I can fix some of these issues.
Another issue is that Dorico’s guitar support is not complete: for example, finger vibrato, slides (that play-back nicely) and some others aren’t well supported. You can work around this with custom playback techniques and other tricks (there are a few other threads - I can link if that’s helpful).