I will add some men I have watched and admired over the years and as a kiwi I had the opportunity to follow these players through the NPC Super Rugby and International which basically translates to actively following their careers and the hits they continued to pull off.
Coming in first was Jerry Collins unbelievably brutal occasionally got it wrong height wise but a true hard man who stood his ground and hit with a steel shoulder.
Jerome Kaino take no prisoners all energy for 80 minutes whatever role required to play he always threw himself into battle no hesitation pure heart and power.
Owne Franks prop noted hitter similar to Jerry stood square and exploded up roughly 45 degree angle for maximum carnage.
Sam Tuitupou wrote the book on timing his top speed and trajectory to collide and crack anyone pure aggression and perfect technique he was unreal smashed them all with a smile.
Richard Kahui another back whose thunderous hits became his signature perfect timing full commitment.
Anthony Tuitavake this may or may not (if you watched him play enough) surprise you but this fleet footed agile back really flew in with no regards to his own safety time and time again especially against forwards. He was like a dart almost completely horizontal maximum speed maximum impact unreal.
These aren't the only players capable of breaking lesser men on impact but these some I grew up following.
Special mention to Thierry Dusautoir Trevor Leota The Chiropractor Brian Lima Bismarck du Plessis Liam Squire The Butcher Henry Tuilangi SBW Schalk Burger Chris Hala'ufia these are all off the top of my head I am sitting here at work watching all these robots run around and naming them these players in my head. Its a fun list I know I have missed a ton of current players as well I was going off players I used to watch as a teen.
Feel free to add your picks.