When you intend to use all features of Piwik PRO, Tag Manager, consent Manager and Analytics, I would definitively use the integration as it is written by the Install manually (Install a container (with a tracking code) | Piwik PRO help center) , because all modules know about each other (especially the consent manager and tag manager in case of GDPR and the like)
Tag Manager and Analytics work well together when using for instance custom dimensions.