Witch Doctors are not good. Even worse then Flame ones and those are like your “2nd tier” when there really, really is nothing better. (Reason is weapons are somewhat mathematically balanced, so weapons that do only flat bonus damage, like Flame, are usually weak ones because the damage is rather insignificant to not “break things”. FC is scared of that.)
The best bet and what to look for is something that interacts with weapon mechanics because that one you can exploit by proper weapon using (meaning building the build around the effect, exploiting what it does by using synergies if you can).
Because effect that triggers once a 10s for 3s will still be likely “mathematically” balanced around the average damage the on-hit weapons do. But your build might be able to burst more damage skills or use other buffs into those 3s, giving you the edge over simple Flame which you can’t exploit in any way (and that’s where “on average” math fails).
That’s the general idea.
Now… I do not use ele as main, so don’t know how exactly it can fit into rotation after last changes. But Totemic looks very promising. The damage dot and lightning things are useless. But the cold damage buff might count. It’s same as how people are using frozen figurine (you will have same buff thanks to heat). And that 15 cold might be what makes or breaks the basic build.
Second interesting worth testing would be overclock. That one uses time limited buff. If you can utilize it, like use power abilities on the buff when it happens, and builders/secondary weapon when it’s down, it has some potential. Although random heating may work for or against you.
Infernal Apparatus is what we tried to use back in time when overheating was the impossible problem. It should allow you to get into red zone, cast blizzard to cool your self, cast crystallized flame sinking its serious heat into infernal and one more power ability in red zone without affecting heat, then it cools you and you may build it back. No idea how that transforms into today’s heat management.
Don’t forget that until Mythic (yellow) 35 you can use anything, pips and such don’t matter much. You will need one such weapon anyway for leg fusion, so that’s your opportunity to get used to effects/test how well it handles. Get a feel about heat management if more/less would be better. And gives you time to look for other weapons.
Sinking money for a weapon you are not sure you want/can handle now is not worth.