Cellunlocker.net has always provided fast service when unlocking my Android/Blackberry phones. I haven't used them for iPhones as yet though, so I can't comment on their service for them.
For my iPhone 5S, I used Chronic Unlocks. It was pretty expensive, and the service has been terrible. They quoted 2-3 business days for the unlock for a Rogers 5S, but ended up taking close to 12 business days. I'd asked for a refund after about 10 days, since I no longer needed the unlock (already traveled and returned) and have now filed a dispute with PayPal. Trying to connect up with their customer service has been terrible too - no one responds to any email sent to their CS department, and one of the few times I heard back from them was when I filed the dispute. My unlock mysteriously appeared a few hours after I filed the dispute..