For me personally it was Messagebird. Two failed demos because of this and the response from them where non-existent. I was even contacted by one of their sales people after I wrote my last "angry I'm leaving" email asking me if I was interested in using their services.
Yes, similar position with Messagebird. Lack of transparency in their reporting/insights vs Twiliio. That said, our Twilio pricing is 2-3x Messagebird.