Cole was replaced by Nicole Scherzinger shortly after filming on the audition stage of the competition began.
The Girls Aloud singer appeared in the first hour of the premiere episode last night, and garnered favourable reviews from critics for her judging style.
Darnell told Deadline: "It's easy to love the one that's gone, but Nicole is great too. Both are stunning but also very different."
Darnell was reportedly instrumental in the decision to replace Cole with Scherzinger shortly after the initial Los Angeles auditions.
"[I have] no regrets," he added. "But I also love Cheryl."
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Watch Cheryl Cole on The X Factor USA below: