I'm gonna be honest, King probably has better durability. Hear me out. Zoro, who seemingly puts both basic armament ( not advanced but still dangerous ) and advanced CoC ( which is said and implied to be far better than advanced armament ) still couldn't slice King with King's flame up. Meanwhile Kizaru, from what I remember, hasn't been hit once in the story but that's due to his speed and fruit. How ever, we can assume he's somewhere near, or equal to, Akainu, while Akainu had blood drawn by Vista and Marco, both not having advanced haki from what I remember, and especially not advanced CoC. He was also momentarily warded off by Crocodile, Jinbe, and Marco. And old white beard beat the ever loving shit out of him and injured him badly.
Basically, Kizaru has comparable durability to the guy who literally can only pick on people with no resistance to his power or have a considerable gap in strength and experience from him, or are literally old and dying from some heart disease. Meanwhile, King gets shlapped by Marco, and can recover from it, and can then tank attacks that would do actual damage to Kaidou. Zoro had to literally invent a new attack against him, and I think he MIGHT have cut King's flame, but I don't remember that too well. Basically Zoan regen, plus the insane durability it gives him, is better than Kizaru's durability. Also, King should, from a narrative point, be comparable or stronger than Benn Beckman, whp, while having no feats, kind of scared Kizaru, though Kizaru realized " wait I can't just sit here being held hostage by a Yonko commander I might get clowned and yelled at by my superiors " ( this loyalty and dedication to his job was shown in another ways along with other admirals doing the same but I'll get to that soon. ) and stopped playing around with Benn Beckman and got back to hunting Luffy once Benn was distracted. Now, I think he did that because after all, the admirals have been shown to be dedicated to their jobs even when a clear skill gap was shown. Kuzan is exempt from this, since he's lazy as hell lol. But, Akainu, who is implied to be weaker than emperors, had a show down with Whitebeard, and both got equally whooped in said battle, though Whitebeard was MUCH more handicapped. Now, compare this to when Shanks showed up. Shanks is healthy, he's young, and he seemingly has no diseases, unlike old Whitebeard. And Akainu was at quite low hp, too. ( not like him being at full hp would make him beat Shanks since he couldn't beat Whitebeard at full hp either. ) Even still, Akainu likely would have tried to kill Shanks if ordered to, even though Shanks was able to easily block Whitebeard, the same guy who clapped Akainu. it's quite clear Shanks was able to brutally murder Akainu. And I don't know why he didn't, but that isn't the point. So basically, the Admirals are very dedicated to their job, in case someone tries to argue that any admiral besides Kuzan and ( sometimes ) Fujitora is lazy and not truly loyal. Oh, and also, in case someone claims " b-but Aramaki roflstomped King and Queen in seconds!!! " my brother in jesus, God, and the holy spirit ( if you for some reason believe in the trinity ig), he literally used incapacitating hax on them while they were still in base form, and sure, Kizaru is comparable to him for obvious narrative reasons, but he doesn't have the same hax. Also, he just did the same thing as crocodile, that can be solved by giving king and queen some deer park water bottles lmao. In conclusion I think King has far better feats than Kizaru so far, and sure some of these claims can be refuted, but others are very solid imo. If I made any grammatical errors or anything, point them out, since I'm on a tablet and it auto corrects one piece names. For example: Lizard is what I get for Kizaru, among other words. And Also is what I get for Zoro.