Normally I say, what is in your roster, but yellow 4* heroes are a sorry bunch.
Danzaburo
Danzaburo.
But only after you get Wu Kong to 4* 4.70 .
Jackal is not great on defense, even if you have 2x Jackal 4*+1 ( see below ).
But Danzaburo is good on defense, attack, and class quests.
Eventually you will get more 3* Orbs, and you can level 1x or 2x Jackal to 4* 4.70 .
But I get much more use out of my Danzaburo 4*+1 than my Jackal 4*+1 .
Jackal
I only have 1x Jackal 4*+1, but I am slowly chasing 1x Falcon ( Retired 2 Play / Return On Investment 2 Play / Free 2 Play ) so I might get a second Jackal.
If I ever get 2x Jackal I will level them both to 4*+1 just like 2x Valeria ( also only have 1x Valeria 4*+1 but desperately want 2x Valeria ) because 2x Jackal 4*+1 is awesome. Just like 2x Valeria, they combo beautifully together.
Just like 2x Valeria, they are 4* 4.70 heroes so require 48% Hero XP, 50% 3* non farmable ascension items, and 26% of the food cost of a 5* 4.80 hero.
But Jackal is a Glass nuke ( see notes ).
If Jackal is dead, you cannot get the yellow defense debuff. This is why Falcon, Frida, Panther, Evelyn, King Arthur are better than Jackal.
You still get some of the highest normal/ matching/ physical damage of a dead hero ( grave damage ), but several other yellow 4* / 5* heroes also have high grave damage.
