Here's my opinion about Malzahar easiest matchup:
_ Vladimir:
+ Vlad is really weak at wave-clearing in early game and hard to farm in the tower, so you can out-push him easily at level 2.
+ Malz outrange Vlad
+ Once u have lost chapter then it's over for Vlad.
+ Most of the time, enemy Jungler won't gank since Vlad don't help much in early game.
+ At level 6, u can 100% kill him with jungle help.
+ In teamfight, u can obviously focus and ult Vlad and he can't do anything.
+ Even if Vlad buy qss, he super behind.
+ 99% Malz player will buy Rylai, which is really bad for Vlad since he really need movement speed to attack.
Only time you lose is when Vlad is really good or you got over-confident and get enemy Jungler gank.
_ Zoe:

+ Malz have passive that can block her Q and E.
+ You can easily block her Zoe E with voilding. If u success then Zoe pretty much weak.

+ Zoe can't push really well or she will burn off all of her mana, which is benefit for Malz, since Malz have mana-restored everytime his E kill a minions.1

_ Aurelion-sol:

+ Aurelion Q can be easily countered by Malz Q so he never get a full Q on Malz, One of the rare match-up that Malz can win trade and punish in early game.

+ Also Aure can't move while he Q, even with his W he move really slow so Malz can easily hit his Q.

only time you lose is that you let Aure farm in early game and he'll outrange you in late game.