If your into Puro and have a multi-region player I'd recommend a few titles.
Riki Choshu Box set - If you’re a Choshu fan and have quite a bit of cash this is well worth it. 6 discs covering Riki's NJPW career from the 70s to about 00 with a small skip over in the mid 80s due to his stint in AJPW.
Radical Fights - 3 DVDs covering the history of NJPW from 72-01. NJPW does an excellent job in restoring their old footage, unlike a certain American promotion.
1994 J Cup - Great intro to Puro, which has been discussed to death already.
2002 G1 Climax - Two discs covering every match from the round robin tournament in their entirety.
NJPW vs. AJPW Total War - 2 discs covering the 10/9/00 & 1/4/01 Dome shows.