This is a loaded question right?? LOL! I will try to be specific.
The most upside potential is between TENG / GST
The best run company is Range Resources.
The company with a lot of room to run,agressive plans and a good balance sheet, is my baby REXX.
A upcoming IPO is Eclipse Resources from State College, Pa.
I feel all of these offer great long term promise. I like TENG after many years of stress and strife, they should be positioned to finally move forward.
I like to speculate, so I look for poorly managed company's with a great asset base, good industry partners and new faces in management. Most times over the long haul your returns will be very good following this model.