Primal Surge, firstly.
Rather than gaining Wild Shape they get a battery of choices, and Wild Shape is just one of those choices. That, alone, catapults this into the top position for my favorite Druid since 2nd Edition AD&D. You even get two choices right away and can trade them whenever you level up.
And the other options are, truly, amazing. I'm not even kidding.
1) Do a Ritual spell in one round without expending a slot.
2) Upcast a Spell even if you don't have the slot to do it. (by 1 level)
3) Create a pillar of elemental power for 2d6+Level, and gain more pillars per use with additional levels.
4) Find Familiar on a natural creature with a single action
5) Plants overgrow a scaling radius and create difficult terrain that moves with you.
6) Wild Shape
I am going to mercilessly pillage this design with full credit to LaserLlama because this is just -how- Druids should work, rather than all of them invariably turning into a Bear or whatever to wade into melee.