Play video content EXCLUSIVE TMZSports.com

Dana White says he wishes nothing but the best for Demetrious Johnson now that he's leaving UFC for another MMA promotion -- and tells TMZ Sports he hopes DJ finally gets the respect he deserves from fans.

The UFC worked out a trade with ONE Championship -- in which Johnson will leave UFC and in exchange, ONE has sent over their welterweight champion Ben Askren.

Johnson was a beast during his UFC run -- breaking the record for the most title defenses -- but he was never the pay-per-view draw a fighter of his caliber could have been.

We asked White how DJ would be remembered in the UFC -- and he told us, "I feel like he never really got the love and respect he deserved from the fans."

White added, "I don't know if he was always thrilled being here, so hopefully, he's a lot happier where he's headed now."

As for Ben Askren -- who's undefeated, 18-0 as a pro fighter -- everyone wants to know who he'll get first in the UFC.

"We're still working on it," White says ... noting, "He's definitely gonna fight somebody in the Top 5."