Has anyone compared the two Sparkpost extension?
I've used them both. CiviDesk's version wins hands down on ease of installation as you just install and plug in your API from SparkPost. Also if I understand it, sending via the API is preferred.

PESC's version requires installation, update SMTP settings with those provided by SparkPost, and then configuring a Scheduled Job with API and other configuration settings.

One issue I am noticing on a site with CiviDesk's module is a high bounce rate reported in CiviCRM (bounces of type "Syntax") which are not actual bounces in SparkPost - but I may not have had the latest version. Testing now.