So my general rule of thumb is   1. Kick Returner 2. Kicker 3. Punt returner( this is who I recommend since there are few apart) 4. Punter( this one last since I personally never punt)

So considering usage I would say kick returner or kicker. However, if you are looking to boost your overall and or if there is a good boost go for punt returner or punter.

But again it all comes down to personal use and how there boost work with other players in your line up.