Mine is (left to right) Rigard, Kingston, Magnu (costumed), Grazul, and Joon.
Reason why is because I like the mana-consistency of a Rainbow team, it keeps a stronger healer with Cleanse in my party, along with a weak (but fast) healer with an omni-block against debuffs, and three Fast Cannons, which charge up at about the same speed, and only two of which need to be charged to kill any one Hero (usually) in a single turn.
In addition, it gives me two offensive debuffs that mitigate incoming damage (-50% attack and Blind), and one that lowers enemy defense, for extra “Uumph” in my follow-up.
In my opinion, it’s a very reliable all-purpose line-up. But I’m open to suggestions to improve it.