The 28-year-old has played an integral part in the Welsh club's consolidation in the Premier League and Coleman believes that his national captain deserves more recognition for his recent good form.
Coleman told the Daily Mail: "There is not a better centre-half in the Premier League.
"People may look at Ashley and see him playing for Swansea who, while they are a Premier League club, are not Chelsea or Manchester City, which may make it harder for him to stand out playing for a smaller club.
"But there has not been a better centre-half performance-wise over the last three months and I am not just saying that because he is captain of Wales."
Williams began his career in non-league football with Hednesford Town before he joined Stockport County ahead of his move to Swansea in 2008.