Helping a long time Vim user try Emacs

I've got a buddy who has been using vim and vi before it for a long time. He wants something that's more automatable and asked me if I could help him get going with Emacs. He's also going to want lsp support in some form. I personally run my own config and use traditional Emacs bindings. I'm familiar with Doom and Spacemacs, but I'm also wondering if I should just write him a simple conf that's pretty much just vanilla + evil + lsp-mode/eglot and maybe a theme. Are there any must have packages besides evil-mode to get him a familiar editing experience? Thanks!

Doom is a good start - it'll give him a chance to see what he likes and doesn't. If it's perfect, great. If not, you can hack up a config that has what he likes from doom without the rest.

I am a former Vim user who switched to Emacs. I think if I started with the default minibuffer completion system in Emacs I would have found Emacs off putting. Along with evil / eglot (or LSP-mode) I recommend at least adding a different completion framework along with the bells and whistles that go along with that (i.e. minibuffer annotations and completion-framework aware command replacements). I started with Doom, and that worked really well for me for around a year. However, at some point I found I wanted to explore Emacs more and make changes on my own. I personally found it easier to understand how Emacs works and how to make the changes I want without the overhead from Doom, so I switched to Vanilla. So if this person is just looking to have an editor they can use, I'd suggest Doom, but if they're the type of person who may want to customize Emacs on their own then Vanilla + evil + lsp/eglot + Modern Completion System imo.

Perhaps is https://emacs.zeef.com an useful resource for your buddy to find what he might need:

Can you elaborate on the modern completion system? Like Vertico and Marginalia and stuff?

I still use the Ivy related packages, mostly because it works well enough for me, but yea, I mean stuff like Vertico and Marginalia.

I came from a fairly similar place, this is a fairly minimal package set to have a useful evil-mode up and running: https://github.com/ideasman42/emacs-for-vimmers

Now that I know what I know I would advice your buddy to go with the elisp manual. He's using vi, so i guess he will grasp it in no time and will go right ahead with automatizing everything by himself. Of course he can and will take a look at other confs. I don't know any other piece of software that is as easily and naturally extendable as emacs. So i don't think the familiar editing experience is the best way. I think it's better to go right ahead for the uncomfortable new strange emacs experience.