Earlier quoted context omitted.
Depends on needs. If great documentation and easy to use APIs are important, then I’d recommend a different provider over one for price / reliability. Also depends what world markets you are focused on too. One other major variance is if you need MMS or short code support.
So which would you recommend for documentation and which would you recommend for price?
Provider based on price depends on how heavily you use US vs World, and if it's SMS (and/or MMS needed) or Voice or both and what volume you are operating at. For pure SMS with a balanced mix of domestic and international, I would probably suggest AWS Pinpoint at this point. Their international rates compared to Twilio are fantastic for all the locations I spot checked.