Most decks run both if theyre aiming for that win condition, but Exsanguinate is positioned much better in the current metagame, where gaining life can often grant you another whole turn that you wouldnt have otherwise had access to
The card itself is also quite underwhelming, which definitely detracts from the appeal
On top of this it acts as removal for all the thing you hate the most - flying creatures
If the result is equal to the Vehicle's mana value, it's sacrificed, dealing damage equal to its mana value to any target
At the very least Zealot gives us the dimension of now having access to 8 Caryatids, which could matter especially as I am playing them in Yorion decks that have a bunch of deck slots
As far as which Commander 2019 deck has the best colorless cards, it's somewhat subjective