Should I change my Character Card Decks?

List of all the cards I have and my current Deck setup:

 Spoiler

I/L - SS
Cannoneer - S
Mercedes - S
Demon Slayer - S
Aran - SS
Blaze Wizard - A
Phantom - S
Evan - S
Mihile - S
Luminous - S
Kaiser - A
F/P - A
Battle Mage - A
Angelic Buster - S
Bishop - S
Kanna - S
Hayato - A
Wind Archer - S
Xenon - S
Demon Avenger - S
Thunder Breaker - B
Dawn Warrior - S

Deck A - S Hero (Aran, Evan, Luminous) HP Drain, MP Drain, +INT, 3 Heroes
Deck B - S Mage (I/L, Bishop, Kanna) +Magic Damage, +%Boss, 3 Mages
Deck C - A Mage (Blaze Wizard, F/P, Battle Mage) Filler deck, +Magic Damage, +%MP, -Damage Taken

Should I change it at all, considering my mains are my I/L and Bishop?

I'd say level your f/p so you can get the s version for it then combine it with the i/l, bishop deck, since its an extra 7 all stats if they're all adventurers in one deck. Then put the kanna one in deck c.

I say replace all the mages except for Evan and Kanna.

Marksman, DS, DA, Hayato, Mercedes and Mechanic are all good options.

Yeah, replace the second mage deck with something else.

I use Mechanic/Demon Slayer/Demon Avenger, Marksman/Hayato/Thunder Breaker, and Kanna/Luminous/FP
Thunder Breaker is just a filler cause there's nothing else I really care to make instead.

I guess I should also mention that I only have 1 open slot and that's for Zero, unless we get a cap increase + free slots. So I can't really make anything new.

Also, I couldn't stand Mechanic, plus I have +105% Buff Duration on my primary main already.

I'm primarily wondering if there's a better setup I could use with what I already have.

Hayato, DA, and DS are pretty much the only things I would think of putting in your A-deck mage pile. You get a warrior set in return lol

Xenon, DA, and DS are all Resistance, so you can get +7 all that way too (too bad Xenon's is +20 all except int)

You only get one class type bonus, so two mage sets does not work.
Also, I find the class set bonus not to be SOO beneficial, compared to individual cards.
IF you have good cards, that ALSO make a set, then use it.
Without remaking new classes, and because you dont have many explorers to class change (expensively):

Deck A - S Mage ( I/L, Blaze Wiz*, Kanna) Level up your Blaze Wiz!!
Deck B - S Warrior ( DSlayer, DAvenger, Mihile/Hayato*) level up your Hayato
Deck C - S [no set] ( Luminous, Evan, filler)

If/when you SS your bishop, change your sets to something like this

Deck A - SS [none] ( I/L, Aran, Bishop) Aran is only for SS
Deck B - S Mage ( Blaze Wiz, Kanna, Luminous)
Deck C - S Warrior ( DSlayer, DAvenger, Mihile/Hayato*) level up your Hayato