Which abilities are worth to be purchased first for V in DMC5? Devil May Cry 5 guide, walkthrough

Your choice of abilities will depend on which playstyle you chose for V. Buy Promotion for V - this ability allows you to jump on Nightmare and control it (V is temporarily invincible).

A good tactic while controlling Shadow is to launch enemies into the air and then keep attacking them with Guillotine.

Buy specific skills for both familiars, but focus on developing only the one you like to use. Shadow is better at attacking single enemies - Arbiter + Bayonet / Guillotine and Hedgehog are especially useful.

Griffon usually lives longer because he flies all the time. However, his attacks are weaker - their advantage is that they can damage a few enemies at the same time. Flank Attack is a must have (it knocks enemies down and makes them an easy target for Shadow). Beside that ability, you also should get Round Robin to protect V (Griffon usually teleports back to V when he charges this attack), and Blockade (charge and then shoot thunders).