The issue with Branding Smite is the the risk/reward ratio. Either the target you want to hit is already invisible, in which case you cast the spell and hold it until you can make the hit with disadvantage, or you assume they're going to become invisible/hidden, in which case you might be giving up the extra damage for nothing.Man I just don't understand why folks are valuing ~1d8 damage so highly. From experience, frightened, blinded, even ongoing damage sometimes (though that one is too easy for the target to get out of early), are well worth doing 1d6 or 2d8 or 2d6 instead of 2d8 damage.
I mean, Branding Smite deals a meaningless shortage of damage, effectively the same damage, as Divine Smite, and the target sheds light and can't become invisible. IDK about you, but I face and use creatures that use invisibility often enough that it's worth it. I also can't imagine how a creature could ever become or stay hidden, while under the effect, since they're shedding bright light, I at least give them disadvantage if they try, as does every DM I know, and in a dark enviroment, a PC with darkvision might have advantage to hit them, since they're a beacon in the darkness.
Searing Smite is hot garbage. You deal 1d6 extra damage instead of 2d8 (as a first level spell), and if the target fails a save you get to do an extra 1d6 damage, leaving you still on average 2 points of damage behind. If you're lucky, they'll fail a second save, bringing your damage up to 1 point above the divine smite. If you're super lucky, and the target isn't dead already, it'll fail a third save bringing your damage to about 5 points above divine smite. Casting it at higher levels just puts you further and further behind divine smite, since the only extra damage is on the initial hit... which would be a d8 on divine smite.
Wrathful Smite can be pretty good, I'll admit. Frightened is a great effect to put on your enemies, especially if you're already up in melee with them. I guess players just don't like the loss of 5.5 damage for it, which I'd kinda disagree with. A conquest paladin should always have this one up their sleeve once they hit 7th level, since it combos with Aura of Conquest.