"Harvest Energy Trust (NYSE: HTE) is exactly what we love – a company with incredible upside and hefty 'dividends' that's being ignored byWall Street," says Keith Fitz-Gerald.

The editor of Money Morning explains, "But the stock is not being ignored by the company's executives. In fact, insiders are buying like crazy. And while this by itself doesn't guarantee higher prices, it's an important indicator of things to come, especially when oil prices are destined to increase in the coming years.

"Harvest Energy is located in Calgary and functions as a Canadian royalty trust, which means its profits are funneled back to investors in the form of 'distributions.' Harvest engages in the exploration, development, production, and sale of petroleum, natural gas, and natural gas liquids in western Canada.

"And the best part is, it's been tamped down in the last two quarters. You see, management has reduced its distribution by 21%, citing volatile energy prices and the new tax rules set to take effect in Canada in 2012. It also carries a lot of debt after having consolidated purchases of other oil and gas trusts and large private producers over the last two years. The company also purchased a refinery complex – and that didn't come cheap.

"Now here's where things get really good: Plain and simple, Harvest is sitting on oil – a lot of it. Large multi-million barrel reserves, with an estimated 9.3 years of proven and probable reserves using conventional extraction techniques. It's also sitting on over 1 billion barrels of untapped oil sands.

What are the best energy investments for long-term investors? To answer this question, I surveyed 20 of the nation's leading financial newsletter advisors to find their current favorite ideas in the energy sector.

Interestingly, the advisors see the best opportunities in areas well beyond traditional oil firms; indeed, no one included in this report chose a major integrated oil company. Rather, the advisors have shown a preference for various oil services sectors, non-oil energy sources, and developing alternative technologies.

Some focus on areas such as deep-sea operations with Diamond Offshore Drilling Inc. (NYSE: DO), Transocean Inc. (NYSE: RIG) and Oceaneering International (NYSE: OII), while others look toward oil shippers such as Nordic American Tanker Shipping (NYSE: NAT) and refiners such as Valero Energy Corp. (NYSE: VLO).

Others chose companies that make specific products needed by the oil & gas industries such as NATCO Group Inc. (NYSE: NTG), which makes a wide range of oil & gas processing systems; Dresser-Rand Group Inc. (NYSE: DRC), a maker of control systems; Gardner Denver Inc. (NYSE: GDI), which makes compressor and fluid transfer systems; Tenaris (NYSE: TS), a maker of pipes and tublar products and Schlumberger Ltd. (NYSE: SLB), the largest and most diversified of the oil services companies.