In my opinion - admittedly as a non-helicopter specialist - the gold standard in military helicopter rescue training would presumably be that used by the US Coast Guard.
Largest, single focus task in the world.
Arguably most severe weather conditions.
They use the MH-60T Jayhawk (qty 42) and MH-65 Dolphin (qty 100) - much more expensive pieces of kit ($17M and $9M respectively).
USCG Advanced Helicopter Rescue School:
https://www.uscg.mil/d13/sectcolrvr/...scueschool.asp
MH-60T:
https://www.uscg.mil/hq/cg7/cg711/h60s.asp
MH-65C/D/E:
https://www.uscg.mil/hq/cg7/cg711/h65s.asp