+1 on Postmark. I use it on nearly all my apps.

While I believe PM to be the best overall, there are 2 limitations that may be big issues based on your use case.

#1 Conditional Text: PM templates use Mustachio which is simple and powerful BUT is limited in terms of IF/Else conditional text (it CAN display text if a value exists but Mustachio CAN’T use the value of the value as a condition for which text to use).

#2 HTML Designer - not available in PM unless you also use ActiveCampaign. That being said PM does provide you with basic layouts so if you’re comfortable editing text within html and don’t need to do anything fancy, this limitation probably won’t be a game changer.