What are the best anti-tank kits for mid laners? I'm not saying who's better in this patch but overall. Is it better to force a Liandry + Rilay's on certain mages you would normally build full ap?
For builds, absolutely build CDR Boots, Liandry's, and Void Staff. Flat Penetration isn't as effective against higher resistances (though Liandry's gets around this due to obvious reasons) so you might as well take the CDR.
I heard Malzahar is a really stupid anti-tank mid laner.
Learn AP Kog'maw mid. Also, Malzahar is good. Cassiopeia is good. Fizz is good. Champions that have %HP damage in their kit. Champions that benefit from building Morellonomicon and Liandry's.
The only issue is keeping the tank from sticking to you. Lux and Morg are good at this, so is Xerath and to some extent Orianna but she doesn't have as consistent of a hard cc.
i'm pretty sure malzahar is up there. high base damage aoe silence with a .8 ap scaling, 5 seconds of aoe % max health in magic damage, high base damage .8 ap scaling 4 second DoT, and a suppression ult that deals moderate damage with 1.3 ap scaling. as well as minions who can tank skill shots and turret shots that spawn every 4 spell casts
is a good choice against many tanks, and that's why you see her top lane sometimes; she obliterates 
in lane with her harass, for example. Plus, Liandries is a good item for her.
Orianna does really well against dive-oriented tanks like Shyvana. Syndra and Zyra, too. Less so against hand holding tanks, tho.
Basically, any champions with very linear movement patterns is gonna have a rough time against those champions, since predictable movement against any of them is going to turn into guaranteed CC and insane burst.
Going for Liandry's is occasionally a solid choice (I believe GBM popularized the Nuker build on Orianna, going Double Doran's into Sorc Boots and Haunting guise to maximize early damage), but Rylai's is generally a champ specific pick, not so much a situational pick for all mages.
Malzahar is the most obvious choice (10+% max hp per tic of pool) Brand is nice as well due to his passive.
Otherwise, someone with cc to keep the tank at bay while you demolish their carries, then either finish off the tank or he escapes. That's team fight stuff though, I'm not sure about 1v1ing tanks. Usually blowing all your cooldowns only gets them down to 25-40% health, assuming you aren't fed, have void/last whisper and are +2 levels up or somethin.
umm i would say zed because you build atleast 2 high armor penetration items on him and you still do a decent amount of damage plus his passive helps and he has low cooldowns for a melt if the tank survives the combo and he builds lifesteal so he won't die in a fight against say a maokai.
