[Kalzazz]

The big difference to my mind is I can use Breath Control to restore FP, I can't do that with ER

That more than makes up for the drawbacks of FP in my mind

Now, if I was making a straight up Imbueist, my favorite build is the 'Blood Ramjet' as I call it

Take good stock of HP.
Take perk for spending HP on Imbues and perk for spending on Extra Effort
Take Vampiric Strike
Go wild wild wild spending your HP on extra effort and Imbues while using your Vampiric Strike and hope for the best!

If you do take ER and Imbues though, take the Vampiric Strike to refill ER