Morne Steyn holds the record for most consecutive successful kicks at goal in Test matches. He had a streak of 41 successful attempts that ended on 6 November 2010 against Ireland. The previous record was 36, held by Chris Paterson of Scotland. He also has the World record for most points scored by a player who has scored all their team's points (31). He also has the most points scored by an individual against New Zealand (31) in a single test.
He has the most points in a Super Rugby season (263) - Beating Dan Carter's record of 221 set in 2006.
I'd say he is a better kicker than Carter. Carter may be a better rugby player but not kicker!
If Morne Steyn were playing for NZ he would have an even better record at the rate that NZ score tries. More opportunities to kick at goal!