He finished first by a landslide.
He came in first with the most votes by far.
He won by a wide margin in the vote.
He topped the vote with an overwhelming lead.
He was voted No. 1 in a runaway.
by far(ダントツで/群を抜いて)
He came in first with the most votes by far.
は「ダントツの得票数で1位」そのものです。
by far は短くて強いです。会話でも記事でも使えます。