Im in a keeper league for fantasy football. Who should I keep out of these 2 guys?

We have to give up a draft pick 2 rds ahead of where we got the guy last yr, so say I got someone in rd 8 of last yrs draft, this yr I wouldnt get a 6th rder this yr. I got Adrian Peterson in the 7th rd so Im giving up a 5th to keep him obviously. But I got Lynch in the 6th rd and would give up a 4th. My other option is I got Michael Turner in the 12th and would give up a 10th, should I keep Lynch or Turner??