Dynasty draft tonight...Mahomes or RB?

I have my dynasty draft tonight and this is the 3rd year of the league. We have rookies and any up-kept players in the draft. I have the 4th pick and looking for some opinions. Would you go with a rookie RB (Freeman, Johnson, or Penny) or would you take Patrick Mahomes who is available? Wentz is my only QB, and my current RB’s are Hunt, Fournette, and D Henry. Thanks!