I started learning him and have been using mostly maul + ex disc + cmd grab.
I also use that combination, which appears to be the best one.
The power of a mid command grab and the ability to reset neutral after f+2,4 with EX disc are too good to pass by.
Maul is a strong tool too because of its anti-zoning capabilities. You can also use the move to make certain strings safe on block against all characters except the rare ones with a 6 frame d+1 like Geras and Sub Zero.
By not equipping the launcher, you retain the base d,f+2, which is an underrated special move with a huge hitbox and relative safety when spaced properly. d,f+2 is also an anti-armor move that does massive damage.
Life has been good for Kotal Kahn since EX disc's flawless block gap was removed. He went from a low tier character to top 10. NRS did a great job buffing him without making him overpowered.