In maddening, your archer needs both STR and DEX since enemies have high AVO and DEF.

I feel Leonie is the best archer for maddening. Respectable STR, awesome DEX and SPD, and a bit of DEF to boost.

Petra is similar to Leonie, but Petra is designed to be on a wyvern. Leonie is designed to become a bow knight.

Ignatz and Bern are good for effect shots, but they don't ever grow strong enough to do real damage.

Shamir is an option, but she usually starts falling behind in STR towards the skip and should be kept as a sniper for Hunter's Volley... she could be a bow knight, but she would be kind of underwhelming.

Felix is a really good bow user because of his STR, DEX, SPD, and crest. Assassin Felix and and bow knight Leonie is a great combo.