My types were not similar, being smaller and less pax capacity, lower weights. But I was also in a position to move to LH seat on a turboprop or RH seat on a jet. For me the jet was a huge upgrade and would open more doors in the future than the turboprop command time would ever do.
I think companies, or better, HR departments still generally tend to look at jet time as worth more than turboprop time, so that could play a role. But self sponsoring the type would be a pretty big con for me personally. Your current company does not have any further progression opportunities beyond LH seat ATR? If they do it might be worth it to stick around.
There no easy single answer as you said, I'm not even sure I added anything useful in this post
. I tend to lean towards the jet with the motto "it's easier to move down in size of planes to fly than it is to move up".