Originally Posted by
Dr_Strangelove
Sorry, when is this fight that you're talking about supposed to be taking place? Nami does not level up E until at least level 3. I usually take a point in it at level 4.
A jinx will push hard at level 1, hit level 2 first and there is simply no way that a kog'maw/nami can win that fight unless they somehow massively outplay them.
Nami can actually max either the heal or e first. Both work, they just have different reasons for doing one or the other. If you have a safe range with little chance of counter-harass, like cait, e can sometimes be the better pick, as it becomes a damage and slow buff that adds more damage than janna's shield at identical levels, albeit in 3 shots. As an example, at level 3 it gives a damage buff of 55 extra magic damage, while janna's at level 5 will give 50 bonus ad.
With more in-your-face laners, like jinx or mf, nami's heal works better because it maintains the ability to both sustain and be aggressive over a longer period of time, plus ultimately benefits the point of a trade by essentially gifting hp at the expense of your opponent's hp.
I've actually found that going 3 into heal, then maxing e after 6 has the best scaling into mid game without sacrificing laning, as there's greater potential on your e in mid game than your w, and the laning usually ends somewhere starting around bot lane's 6, so w's use becomes less pronounced except against a siege comp.