Depending on the situation both can be the case. Because sometimes an extra turn is more worth than 3 additional cards and sometimes you just need the draw but not the extra phases and
Landdrop. So saying one of the card effects is inferior to the other is just to easy. If you want to evaluate this you have to look into example siuations and compare them against each other.
What I assume is that in Legeacy there are more siuations were you want 3 cards more than siuations were an complete turn is needed instead of the card advantage. Also since we
are talking about a limited resource game drawing 3 is an actual win condition which canīt be said for the extra turn in legacy. The reason for this is that you donīt have the same
amount of options you get with the Vintage Mana Artifacts and Lands.