The great thing about Sacred Exorcist is that the Dispel Evil SLA you get at level 4 auto-qualifies you for the PrC, so you can re-train the spell you used for entry without fear of any repercussions.
Loremaster seems a little feat-intensive.
Contemplative, Divine Oracle and especially Paragnostic Apostle are good options, as is Ruathar.
Moonspeaker is also OK, but locks you into a specific race.