I keep it minimal. I use Email Octopus, essentially as a front end to Amazon SES. I’ve used them since 2016 when it was literally two guys running the service.

For my needs I want something I can literally paste completed template code into that will not get in my way and will have decent deliverability. Email Octopus does a decent job on that front.

I will say that I use hosted forms, though I had a bad support experience with my provider there, MailMunch, so I’m thinking of switching to someone else.