Branding Smite

[Vispiliox]

I just started playing a ranged hexblade sorlock today. I know it's a less than optimum build. :)

I was going to grab branding smite, but I realized that with eldritch strike, it looks a little underwhelming.

I'll only have level 3 warlock spell slots, so eventually the branding smite could do more damage (using 5th level slot vs 3rd level slot).

Is the little boost in damage and ability to reveal someone that's invisible or keep someone from turning invisible worth giving up a higher level spell?

Eldritch Smite
Once per turn when you hit a creature with your pact weapon, you can expend a warlock spell slot to deal an extra 1d8 force damage to the target, plus another 1d8 per level of the spell slot, and you can knock the target prone if it is Huge or smaller.

Branding Smite
The next time you hit a creature with a weapon attack before this spell ends, the weapon gleams with astral radiance as you strike. The attack deals an extra 2d6 radiant damage to the target, which becomes visible if it's invisible, and the target sheds dim light in a 5-foot radius and can't become invisible until the spell ends.
At Higher Levels: When you cast this spell using a spell slot of 3rd level or higher, the extra damage increases by 1d6 for each slot level above 2nd.

[Ganymede]

If you want the best of both worlds (both the effects of Branding Smite without worrying about using up your higher level slots), go pure warlock. That way all your slots are higher level slots.

[Tanarii]

Branding Smite is a unified utility combat spell. One you prepare when you know you're up against certain kinds of enemies, or you have more prepared spells than you do slots.

Those both work pretty well for a paladins, who can prepare spells and generally have a high prepared to slots ratio (due to oath spells). Warlocks eventually reach quite a high known spells to slots/SR ratio, so it can work for them too. Off the top of my head seems like that might be even more true for sorlocks. A lot of low level spells known between both classes.

So the real question is how important is it to spend a known spell to keep it in reserve? Invisible foes with good stealth are a pain in the butt. But you have to encounter them for it to matter.

Tl;dr: personally I'd bounce it off my DM