Quick eyeball test shows 1% parry rate per 35-40 parry stat assuming linearity. This lines up well with the data collected on crit stat, which increases crit rate AND crit damage by 1% for every ~40 crit stat. Crit rate baseline is 5% and crit damage baseline is 145% I believe. There was a reddit thread on this a couple weeks back.

So what would you rather have? +1% crit rate/dmg or +1% parry rate? I like crit more. Maybe if parry increased parry strength it would be a lot better.