Sakurai was also the #1 lightweight in the world by Sherdog's rankings after Gomi was defeated by Diaz. Either way, his latter day accomplishments at lightweight, after what was certainly a Hall of Fame worthy career at welterweight, are definitely worth mentioning. And then, even after that, when he moved back up to welterweight, clearly a little small for the division, he pulled off a great, dominant win over a peak Aoki.
These lists are hard to compile, but Masakatsu Funaki and Kiyoshi Tamura both deserve acknowledgement, in my book. Funaki, according to Sherdog's defunct power rankings, was, for a while, the #2 Japanese fighter of all-time behind Sakuraba and was the top fighter in the world for multiple years and a consistent top 3. The fact that he was a top guy among the first wave of Pancrase fighters and still essentially top dog among the next wave, that included guys like Kondo, Shibuya, etc., while many of his peers had fallen off, was pretty impressive. Not to mention, things he seemingly innovated, like the K-guard, are among the most popular and effective moves in contemporary grappling.
Tamura also has a sterling resume and like Funaki, had an uncanny ability to pull off lightweight moves like flying armbars and rolling kneebars. Tamura's career is muddled by RINGs liberal mixture of works with shoots and indeed, some of Tamura's best shoot performances were, confusingly, bouts against people like Khosaka, Kanehara or Yamamoto, whom he'd also had works with. But ultimately, in spite of being hampered by his less than favorable matches in Pride or the lack of a true middleweight division in RINGs, he has a terrific resume.