I think the Priest fits your preferred playing style the most (denial, fast). The Priestess requires much more reactionary thinking (in general), ie heal prediction, poison blood prediction, etc.
I'd recommend battleforge priest with early avenger cleric support (guard meat). Other than that, just make sure you know when to drop what off your forge (staff early) and save 1 mana each turn for burn payment. Aim to stack burns through Malakai's Fire and use your avenger as a guard. If they figure a way past your avenger guard, use it for the 4d 1 pierce. If they drop a huge threat, well, you're in the holy school. Include some fireballs, etc, for finishers.
All that said, the priestess is probably easier, but you don't seem like you'd enjoy her as much. All the info you need is in the above paragraph anyway, so gg.