I also started on the mountain bike and now ride mostly on the road.
I never got into gravel. I participated in a gravel race and group rides, but I always felt it was not as much fun as either road or mountain.
I'm a fan of climbing. Having a commute home with at least 300m of climbing helps.
How about a link to your Strava profile? ;-) I also have s veloviewer subscription like Craig.

A few weeks ago I thought about suggesting a cycling channel in the slack community, but I obviously never did.