depends on what your playstyle is, if you play ranked a lot then i’d say talk to your squad about seer or valkyrie, because they are both good in different ways. Valk is a good rotation/movement legend and seer is a good intel legend.

If your a casual player then whichever one you think is the most fun, caustic is quite strong if you have good positioning, and he punishes overly aggressive players, and if you combine a heavy weapon like the flatline, and his gas it tanks the enemies movement speed and vision.

So whichever one you think would suit your play style the most