Are you near Bass NW? The two basses you mentioned may be in a similar price range, but they are very different instruments.
Essence basses sell a little higher on the used market in my experience, and I would choose one in a second over the Epic. It is a neck-through bass and the electronics include the Alembic filter, which is key to the Alembic sound. It may seem like having only one tone control knob would be limiting, but there is a surprising range of usable tones.
The Epic has an unusual body shape. Some people like it and some people don't. The neck woods will typically be the same as in a new Essence, but the neck is glued in to the body. These basses have the more traditional bass and treble knobs for a great variety of tones. Epics can often be had on the used market at or below $1000, so they are the least expensive first Alembic. Also, while less common on the used market, the Orion bass has the same electronics as the Epic and a more traditional body style. These basses are a good bargain if you can find one used.
Based on the above, I consider the Epic to be a high quality bass for the money, but it is relatively unique in the Alembic line. The Essence is the real entry-level Alembic. If there's any kind of Alembic dealer near you, see about getting there to put your hands on one. Buying a bass with which you are unfamiliar site unseen is always a gamble.
