He is a mid-tier mdps for daily questing. That puts a few choices on the board:
Sariel- will take the role of boss-killer. He can boost the ABV also.
Canna is an alternative boss-killer. She can debuff bosses, but harder to get.
ET slot can be given to Cano, Amy or Rosa, depending on your playstyle. Amy is for active gameplay, she can be kinda tiring to play during daily runs, but overall she is hella useful.
Cano is way more passive with higher defensive utility.
Rosa is pure passive offensive support.
Of cource there're basic "non-meta" choices- bringing a full tank char, hyperboosting with Lisa/Cass and stuff.
But basic package of Arch+Sariel+ Amy should be fine overall. Arch is great for daily questing (like Armo daily, Illisia daily, etc) with his huge AOEs, Sariel is a meta boss-killer for daily raiding, Amy is a great support with high utility potential.