Pain lands would be my first choice (
Sulfurous Springs,
Underground River etc.).
In my opinion they are the best budget lands going and are perfect for EDH. The 40 starting life all but negates their downside and allows you to build a fast and flexible multi colour mana base without losing out on tempo.
They're not that expensive, but their price continues to creep up and reprinting them into the ground would really help this.
Not only that, they also show new players the value of treating life like a resource.
After that, probably check lands (
Isolated chapel,
Drowned Catacomb etc.). These are in a similar spot to painlands. Not overly powerful but a solid budget option whose prices are creeping up and could do with a reprint.
They also do a great job in teaching new players the importance of sequencing.
Completing the Tango Land cycle (
Prairie Stream,
Canopy Vista etc.) would be my third choice. They have the basic land types so have random synergies with things like
Kor Cartographer or
Three Visits or
Farseek etc.
In terms of ramp, Talismans would be my go to again. They are essentially the rock equivalent of pain lands and have all the associated positives of them too, as well as having the same need for a reprint.
I made a Breya deck that had all of the available pain lands and talismans in and it runs like a dream. It hurts me quite a bit, but runs incredibly smoothly considering it's 4 colours on a budget. Those would absolutely be my personal inclusions if I were the one in
charge of making that decision.