welcome. first off, in ESO everyone is using magic. does not really matter if you use stamina or magicka to fuel your skills/spells.

You can do it with all classes imho.

Sorcerer: Armor buff(s), Weapon/spell damage buff with Heal on Crit, good sustain etc... Can go stamina or magicka (lightning themed basically)

Dragonknight: armor buff, weapon/damage buff (for group), close range fire damage spells single target and AoE, good damage based self heals (embers, flame lash, Inhale)... (fire or poison based theme).

Templar: well, think of a Paladin or Cleric. Holy/Magic damage, strong heals for group too if you go the magicka route

Warden: very versatile for both magicka and stamina. you can use a pet (bear companion), can buff armor/resists, do cold damage (and magic damage mostly). also has some nice graphical effects (like angel-wings of ice).

You said no Nightblade, but you can also play this as a magickal knight/tank type, but with a more poison/disease/magicka type (more like a Reaver or Shadow Knight from other games).

choices... ;-)

I have all classes and play various roles with them (tank, dd, healer, stamina / magicka whatever). I wish there was a 1-handed magicka based weapon you could pair with a shield, because as a heavy armor magicka user you cannot refill your magicka with heavy attacks unless you equip a staff (ice staff tanking is a thing, but does not fit well for a dragonknight for instance, I rather use fire/lightning).

you cannot change classes at the moment, but you can respec race, attributes and skills, so just try out what appeals the most to you.