That depends on what subclass, exotic, and perk loadouts you want to use. I tend to go for max int/dis with my Voidwalker. If I am running voidfangs I will prioritize dis>int>str with str really being ignored. Same would go for nothing manacles. If you are running obsidian mind (which is only worth the exotic slot if you get at least three kills with each nova), I would prioritize int>dis. The perk loadouts on Voidwalker will not really affect your stat distribution. For Sunsinger, it's generally dis>int>str. The one caveat would be to prioritize str>dis if you are running claws for double flame shield. If using starfire or HotPF, I would go dis>int>str. You *may* want to proritize dis>str>int if you play a really aggressive radiant skin build and are going for multiple melee kills in a single radiance. For stormcaller, there is a little more variation. I've recently been going dis>str>int and running transcendence. You want both abilities charged as often as possible to take full advantage of transcendence. Plus, like you mentioned, thunderstrike with amplitude is always nice to have charged. Try claws with str>dis>int for a nice melee build. Otherwise, I go int>dis>str with impossible machines. Hope this helps a little.

Personally, (though I hardly play Warlocks anymore) I built Intellect and Discipline. I will always be able to use a grenade or super, but melees have more limited use. If you want to use Strength, I'd use Monte Carlo instead and/OR the Claws of Ahamkara. Their melee is amazing, but most of the time, you should not be in melee range, and if you are, you typically have your melee, in my opinion.

It really depends on the game mode you play the most/subclass. Tell me these.