Sterling Volunteers
Pros - very fast; nationwide search (important for us because we have a lot of people relocating from other states); they perform a complete criminal locator search with OIG/GSA, which our general counsel required (I had to match the checks our HR department was performing)
Cons - I have a base price, which is kind of expensive in my opinion, but still less than what it costs our HR department thru the company they use. Some states charge an extra fee for aliases, so that increases my cost.