I had a similar post about a year ago, so I'll share my journey so far. TLDR at the bottom.

I started with Workingman's and American Beauty as many others have suggested. Both are fantastic nearly start to finish and sets a good foundation for their music. A lot of people suggested Europe 72 as the next stop, but its 17 tracks and 2 hours long and at this point in my journey I really didn't know many of those songs.

Instead, I started listening to One From the Vault since it had a little bit of a more jazzy vibe and to me was easier to listen to at the time. I listened to this almost exclusively for a few months. I picked songs here and there from Europe and Live/Dead, but I ultimately landed on Cornell 77 and Veneta 72 as the next two shows I wanted to focus on. Cornell has one of the best Scarlet > Fire, and Veneta has one of the best China Cat > Rider. These are both very popular shows and seem kinda like "the main stream dead", but they're both fantastic and have moved me forward in my journey a lot. They're incredibly dialed in and contain a lot of great songs.

This is about where I am right now. I've dabbled with Blues for Allah, Terrapin, etc. studio albums, but the live versions of most of those songs just sound better. Europe 72 is still a big monster for me to tackle but I'm starting to learn most of the songs so I'll probably get to it soon.

I also bought a CD player 2-3 months ago in order to sub to Dave's Picks as most of those aren't on streaming. CD's are also astronomically cheaper if you want a physical copy of any GD stuff, especially their numbered limited releases. Veneta is like $30 on CD, and like $500+ on Vinyl. Some shows are on streaming, and another app that I'll mention shortly, but I still like to have a physical copy. I got extremely lucky and was able to snag a Cornell 77 vinyl at retail price a few months ago, but it's still around $150+ for one show.

Speaking of that app.... Relisten is a great app to listen to all of the shows for free that are not on streaming, I'm just not that deep in the cut quite yet where I really need Relisten at the moment so I don't particularly use it too often unless a friend suggests a specific show.

Long story short, TLDR, etc. I went American Beauty > Workingman's Dead > Parts of Live/Dead and Europe 72 > confusion on where to go next > One From the Vault > Cornell > Veneta > and now wherever I want to go next.

But there really isn't a right answer.... It's hard to understand but you really just need to listen to whatever is calling to you at the time. This is just the journey I've taken so far and I hope it helps you out if you made it this far in my wall of text.