As a global glut sends oil prices into bear market territory long-term investors should be considering picking up some of the better names in the business on what many think will be improved conditions ahead.

A bear market is defined as a 20% price decline, which for oil occurred when it slipped below roughly $42 per barrel.

Bank of America analyst Doug Leggate said in a report last month that any weakness in oil prices is an opportunity to revisit the sector, "but with greater emphasis on stock specific opportunities and dislocations given the overall sector strength since the start of the year."

The analyst had five companies on his pick list,  topped by Hess Corp. (HES) - Get Report . He thinks the company's shares are undervalued by around 37% compared with his price target of $85, which he recently increased to include the value of its stake in its Liza discovery in Guyana with its partner Exxon Mobil (XOM) - Get Report . He added that the 70% oil-levered company has one of the strongest balance sheets in the sector.

Devon Energy (DVN) - Get Report is next on his list despite having made some "ill-timed" acquisitions. But he believes the company's portfolio looks very different now, having sold assets to pay for those deals, and that the company is ready to boost cash flow growth by adding rigs at a modest pace when oil prices improve. He has a $55 price target on the stock, versus its closing price Friday of $38.28.

The analyst also likes ConocoPhillips (COP) - Get Report , which he says has an emerging portfolio of large scale projects that could substantially reduce sustaining capital to a break-even level at around $45 oil, which could lead to cash flow growth per share later. He has a price target of $71 versus a recent $40.82.

Leggate also notes Continental Resources (CLR) - Get Report , which already has performed well this year but still has some room to run with enviable positions in the Stack and Scoop plays (he targets $55 versus a recent $44.05); and Pioneer Natural Resources (PXD) - Get Report , which has low debt and leads with new rig additions following the coring up of acreage in West Texas' Midland Basin, including an acquisition from Devon. He   has a $200 per share price target on Continental, which recently traded at $162.57.

Leggate's picks among smaller companies include Parsley Energy (PE) - Get Report , which is expected to add two rigs that could drive production growth to 27% with valuable properties in West Texas' southern Delaware basin and he has a $32 price target on it, versus a recent $28.51); Concho Resources (CXO) - Get Report , which is boosting production and rig count and has under appreciated land positions in the Midland and Southern Delaware basins, which he expects to hit $139 a share compared to its recent $124.20; and RSP Permian (RSPP) , which is also expected to boost its activity in the Permian and carries a $41 target versus a recent $35.95 handle.

RBC Capital Markets' best ideas list includes Concho as well as Noble Energy (NBL) - Get Report and Newfield Exploration (NFX) among U.S. exploration and production companies; Enterprise Products Partners (EPD) - Get Report and Magellan Midstream Partners (MMP) - Get Report among midstream, or infrastructure, companies; and Schlumberger (SLB) - Get Report , Nabors Industries (NBR) - Get Report and Fairmount Santrol Holdings (FMSA) among oil services providers. It claims its global energy best ideas list is up 14% versus the S&P Global Energy Sector's decrease of 15%.