Runner up Marcus, who was mentored by Gary on the last series, said the 'Greatest Day' hit maker brought "something new" to the show.
"I don't think anyone else could replace Gary Barlow on X Factor," Liverpudlian singer Marcus explained. "He brought something new to the table he was a musician and a really accomplished songwriter.
"He's passionate about music and understands it from a performer's point of view, it'll be difficult to find anyone better!"
But there have been doubts over whether or not Gary would be back this year, after admitting the pressure and work load was far harder than he had expected when signing up last summer.
But Marcus, who has been working with Gary on his debut album, added: "I think Gary was misquoted, it wasn't that he didn't enjoy it, there was just a lot of stress going on.
"We really enjoyed working together and he got on with a lot of the other contestants."
He told Yahoo: "It was amazing when we were working together, he was always coming up with new ideas - he's very friendly and has a laugh with all the staff he's unaffected by how big he is."
Gary confirmed last month that was "in talks" to come back on the panel this year, with tabloid reports suggesting that ITV1 are prepared to double his current £1 million paycheck.
Marcus meanwhile releases his debut single, Seven Nation Army, on Sunday.