TNB good question - but also the wrong one. Wildpilot has the right idea.
My multi-crew turboprop command time was the most rewarding and the most enjoyable. It also gave my confidence a boost as a bonus.
I feel that command experience is beneficial for a jet F/O to have. It makes you appreciate and understand the operation more clearly. Sometimes the role of a Captain is not obvious, especially if you haven’t been one before. The biggest difference is the responsibility, and how that affects decision making. It’s very sobering when something goes wrong and you’re in the left seat. No amount of ICUS or co-pilot time can substitute for that.
Enough drunken rambling. All I can say is that you won’t regret going for a turboprop command. It’s more rewarding than being a jet F/O, and more fun than a Jet command.