Welcome back to the club. I've been using Emacs continuously for almost three decades, 99.9999% of the time text-only (whether Linux console, X terminal console, xterm, or SSH client) on a remote server. My email client is VM, written in Emacs Lisp. I've used it to read mail for almost as long as I've used Emacs. I tried Gnus a couple of times for Usenet but stayed with slrn because of Emacs's lack of multithreading. I've never tried Gnus for email because VM has always met my needs.

VM (and ancillary tools, like Personality Crisis and mairix)

* does a great of job displaying HTML messages. For the very few that it doesn't, one keystroke sends the message to my web browser running locally.

* sends URLs I select (all from the keyboard) to the web browser

* opens images and attachments

* auto-adjusts the From: line of outgoing messages depending on the recipient

* archives messages to various folders using various criteria

* searches my archived mail at lightning speed

Of course, I can write Emacs Lisp code of my own to extend any or all of the above.

VM isn't perfect. I'm sure that I could do all of the above with Gnus, and quite possibly am missing out on other features that VM lacks. Overall, though, I really feel like I have a superpower for email handling with it.