A cool thing about the new Controversy Index tool (hover your mouse over the score!) is that it also measures non-controversy…

[Video][Website]
[6.29]

Patrick St. Michel: This is the first song BoA has ever composed herself, and it bears the markings of a veteran who was pushing K-Pop long before “hallyu” became a buzz word in certain circles. She works in a few electro-pop details to match the dominant sound of Korean music today, but the bulk of the track rejects digital noises in favor of fragile piano and guitar. Whether because she’s been competing with similar artists for a decade now or because BoA also has international markets in mind, this sounds a lot like the mid-tempo R&B that has been popular in Japan for a while, “Only One” sounding a lot like a more developed Kana Nishino track. What makes this stand out is her voice, which just commands attention here.
[9]

Jonathan Bogart: I kept thinking of Aaliyah — not just because of “Enough Said,” but because the dance version of BoA’s video effectively functions as a tribute — and that helped me hear “Only One” not as a disappointingly sweet-and-polite semi-ballad where I was hoping for bonkers dance-pop, but as a stylistic tribute to late-90s R&B, lovable not for the specificity of its vision but for the specificity a listener can apply to it.
[6]

Anthony Easton: I have yet to decide if it is thin or delicate, reductive or elegant, worn through or reinforced via adherence to genre, and how exactly electronic that piano is, and how much that matters. 
[5]

Brad Shoup: A fine if only tasteful dessert, lightly dusted with R&B. Midway through there’s a near-dissonant cello approximation… it’s a neat sonic choice, possibly better than slotting the refrain first, pushing BoA to the top of her range and pulling the emotional rug out from everything to follow. 
[7]

Will Adams: I preferred BoA when she was appropriating Blackout (and well!), but this is pretty and carries enough weight in its low end to save it from floating up to the sky like a balloon. My favorite part is when her voice grows so thin for the title that it can’t be anything but endearing. The rest is respectfully insubstantial.
[5]

Iain Mew: The song is lovely, but BoA’s approach to singing it and especially the production are so reserved and controlled that there’s something too ornamental about it. It seems to actively resist interaction or memory, though it declines very kindly.
[6]

Alfred Soto: Not only is it pretty but the rhythm and multitracked vocals work in conjunction. The strings are a nice touch. Mariah Carey should study BoA’s use of husk.
[6]