Jet FO.
The turbo prop command is the end of the road until you change fleet/job where you will start as an FO again anyway.
The above holds true assuming you are talking about main stream RPT jet FO and not obscure small business jets (IMO)
For what it's worth I do believe the turbo prop command will make you a better pilot and enhance your skills for the future, but it wont help your CV or career so you might aswell skip it of that's an option.