Barclays says it's the best buying opportunity in 20 years for these oil stocks

It's the best time in two decades to buy oil service stocks, even as the Iran war is showing signs of coming to an end, according to Barclays. The bank upgraded the U.S. energy service and technology sector to positive from neutral, and raised oil service providers such as Halliburton and others to overweight from equal weight. "As global markets withstand an unprecedented global supply shock, we believe the effects on the oil markets will reverberate for many years," analyst J. …