Nannes is a lot better than Rankin.
Rankin plays for Ireland internationally and for Warwickshire domestically in Division 2 in England. He averages 29.39 in FC. But take away his record for Ireland (20 wickets at 17), and his stats are poor. He has 21 wickets at 41 for Warwickshire, but did take 10 at 29.2 for Derbyshire when he played for them.
Nannes, on the other hand, averages 24.77 overall. And he has not represented Netherlands in FC cricket. 20 at 19.65 for Middlesex, and 69 at 26 for Victoria. That's England's Division 1, and Australia's Domestic competition.
It's clear to see Nannes is the far superior bowler as far as FC games go, with better figures in tougher competition. Rankin is a decent OD bowler, but Nannes is a far better bowler.