Goldvein Pick is my first choice of the two, given it has the lower equip cost, but either (or even both) might be right for your deck
No creature that has a color can block it, making it a guaranteed hit of four damage every turn
Unless you have an absolutely massive grip of cards, you'll usually be milling for seven or eight cards for six mana, which isn't a good rate
Exile is often been a place to temporarily hold cards for other abilities like suspend, adventure, and flicker effects
Pull rate from Regular Packs: 5.69% The estimated pull rate for Irida (Triumphant Light) from a Regular Pack is approximately 5.69%, meaning you might need to open around 18 Regular Packs to obtain it
Volo, Itinerant Scholar rewards you for building a toolbox of creatures with different types