Good Lord, Philander is underrated.
He was twice the bowler Wagner is (metaphorically not mathematically )
and that is not an attack on wagner, Wagner himself is a great bowler.
Philander was great everywhere except Asia.
Hard to compare as they do different roles. Wagner does all his work with the old ball as a 3rd seamer and is more effective as the test goes on. Big Vern will take you out early in the test with a newer ball.
Wagner is the third pacer while Philander was the first.
Wagner probably hasn't opened the bowling attack in his international career till now while Philander I believe never came in as first or second change bowler in Tests(his t20is in 07 is a different story)
Philander is like Matthew Hoggard of 2005 Ashes while Wagner is Simon Jones. Weird analogy though.