Hi,
I've been a Twilio pioneer as I have worked with them for over 2 years and currently manage accounts with expenses of more than 2,500 USD / month. I have had experience using Programmable SMS, Programmable Voice, SIP Trunking and TaskRouter.
As for Sinch, they are basically following Twilio, so most of the API calls resemble each other.
I am very familiar with their API and I normally get "Early Access" to some of the products they are about to launch lie Facebook Messenger for Programmable Chat, SIP Registration for Elastic SIP Trunk and SMS number in newer regions when they launch.
I would suggest to have a conversation to understand what are the milestones in your roadmap where I can help and I am sure I will be able to complete them in time and budget.
Regards,
Paco