I use Spark for email on iPad and iPhone (and macOS). It’s a clean-looking email client with many power user features that doesn’t get in my way when I’m not using them.
Readdle (the developer behind Spark) just released a new update in which they introduce templates. Templates are for all those emails you send with the same type of contents. Instead of writing or copying them over and over, you create a template with placeholders that are automatically replaced with real data when you send it. If you send a lot of the same reports, email replies, company updates, quotes, and the like, you probably should take a look at templates in Spark.