Dale Steyn for me is somewhere is the top 15 bowlers perhaps, maybe top ten.
I give him credit for being a fantastic match-winner. But he was dominated too often for me to put him in with Marshall, McGrath, Hadlee and Imran, who I put as the top tier. He had a tendency to blow hot and cold in the same series. In India in 2010 for example, he took that amazing 10-fer in Nagpur but seemed pedestrian in the next test. In Australia in 2012, he was taken apart in the first two tests before ripping into Australia in Perth. If you study his career, this was his tendency, a single match-winning performance in every series.
People point to his terrific strikerate but ignore the fact that his R/O is quite high. This means if he wasnt taking wickets, he was usually going for runs. Whereas guys like Marshall, Ambrose and McGrath would still manage to keep things tight even when they were not getting wickets.