Different kind of oranges.
Cara cara has a bigger fruit and the fruit is seedless also so in this sense is better. Blood oranges are often very small, a little bigger than a tangerine and will have seeds often
But smaller fruits are better for growing in a pot. Less weight, less broken branches. Cara cara can have a few thorns also.
Blood oranges are more decorative in a pot, because they have a stunning red skin.
Cara cara "should" taste better because is a navel orange with red lycopene (a carotenoid) and is sweet; whereas Blood oranges should have more complex (tart) flavour given by purple anthocyanins (a flavonoid) that are astringent. Some people like it a lot, other not so. As Antocyanins are a defense against frosts, need some cold to produce solid flesh coloured fruits instead a mottled aspect. It seems that Vanilla Sanguigno does not have a very dark pulp. The darker the flesh, the more astringent the flavour...
... And more stunning "blood" juice in a glass. It seems that Vanilla Sanguigno does not produce a red juice. The juice of Cara cara has the usual orange tone. In this sense looks like a tie.
If Vanilla is a blood orange selected to lose the blood traits (tart flavour, red flesh and dark juice) that make blood oranges interesting, I think that the seedless, bigger, and more uniformly coloured inside, Caracara is a clear winner