Morgan replaced Larry King as the anchor of CNN's 9pm ET hour in January and has so far conducted chats with the likes of Howard Stern, Simon Cowell and Paris Hilton.
The British journalist, however, pointed to his interview with Oprah Winfrey on Piers Morgan Tonight's first telecast as particularly important because it helped generate tremendous publicity for the series.
"I still think Oprah was a great way to launch the show to a bigger audience," he told the Chicago Sun Times. "People said to me afterward that I was either too soft or that they were surprised by how hard I was. There was no middle ground. It's exactly what you want to be."
Morgan also singled out his February discussion with Sheen, where the actor openly criticised Two and a Half Men creator Chuck Lorre and CBS president Les Moonves.
"I'd say the Charlie Sheen one, for sheer live drama excitement, and also because by then I'd been getting a bit fed up with the fact that he doesn't do [all his interviews] live. Two-thirds of my show so far have been live, and I love live TV. Most of Got Talent ends up being live in the summer. Having Charlie walk in and go live for an hour was electrifying," he said.
Morgan announced this week that his wife Celia is four months pregnant with the couple's first child together.
Piers Morgan Tonight is broadcast weeknights at 9pm ET on CNN and at 8pm GMT on CNN International.
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Watch a clip from Piers Morgan's interview with Charlie Sheen below: