Mineral rights - To Lease or Sell

Hi, this is a question is concerning leasing / verses selling Mineral rights in McClain county OK. what should I expect a reasonable offer to be ? Section 10- T5N- R1E. My family and I have inherited 25.72 acres with only 12 NMA, and have been contacted by HELLER OIL in 2014 with lease offer, and recently Wake energy to purchase. any information on these companys will be appreciated and a going rate might help us with our decisions. Thank You