This is what I run with Ember. Whether it was Draco (RIP on PC) or Hieracon (or pretty much anything that isn't a sortie), I tend to do top damage unless there's an Ash or a Mirage running around with a Tonkor, even with only 100% power strength (plus Energy Conversion, of course.) It's just what Ember does when built correctly.
It's my opinion that you don't really need much duration for Ember. Pure efficiency will take care of your WoF costs on both activation and over time, and also let you cast a lot more Accelerants. And my Accelerant even with a full Fleeting Expertise still lasts about 30 seconds, which is plenty of time. Even with a regular maxed out Continuinity you'll still get about 25 seconds of more damage, and a good bit of the utility from using it in the first place, at least at higher levels, is the little stun it gives on hit.
I've also found that Stretch gives WoF and Accelerant plenty of range. Cunning Drift is a good option, but I don't think the little bit of extra range is enough to offset how good Handspring can be. I think you don't really need a lot of range because WoF only ever hits five enemies at once anyway. You might want a ton of range if you want to stay out of the way of really tough sortie enemies - but really, I don't think Ember is much of a sortie frame. Not mixing Overextended and then Transient Fortitude to help fight the strength loss also lets me put on two defensive mods. Can't do damage if you're dead, right?
Firequake is amazing. You can't always count on fire proc stuns from WoF itself, and you don't want to be spamming Accelerant for the stun. It's a guaranteed knockdown on up to five enemies. It actually makes Ember a lot more useful at higher levels and more survivable in general.
No one mentioned an aura, but I use Corrosive Projection. It just makes the most sense for Ember, who will almost always have WoF activated and so will not be benefiting from Energy Siphon. I do like to keep Zenurik active though, so that in case I do run out of energy, I can get back to a reasonable level pretty quickly. It also gives the option of turning off WoF and spamming Accelerant, if a lot of stunning is required.
I am also not sure about how Ember's passive works with WoF. It's not something I want to rely on, but if I get to a tileset that's on fire, I will recast WoF after burning myself and picking up an energy orb. Why not?
So yeah, Ember is pretty great. Someday I'll max Redirection and Vitality. Maybe.