In most cases you should start by increasing Link’s health, but having more stamina means you can climb higher and glide farther, which can be very beneficial later in the game. Horn, moblin guts, etc. In Breath of the Wild, getting more heart containers is directly tied to increasing Link’s stamina, meaning you can only increase one at a time. Cooking 4 restless crickets with one monster part (bokobolin
They can be found in Karkariko village (which I know you've already been too), and "cooking 5 of them in a pot will give you full stamina recovery and 2 extra wheels". I would say this qualifies as your best/easiest thing to obtain. The first one on the list is Endura carrots. If Link instead uses his Lights of Blessing to. They list the top 5 things that can be used to help with stamina. Link can obtain up to 30 Heart Containers from Goddess Statues, allowing him to have a maximum of 40 hearts.