1) Elf Sorcerer
2) Halfing Fighter/Thief
3) Half-Elf Cleric/Ranger

4a)Gnome Fighter/Illusionist
4b)Human Berserker13>Mage
4c)Half-Elf Bard (Blade)

I'm looking for a backup arcane spellcaster to my Sorcerer protagonist, who can be good in combat as well.

The Gnome gives me great saves, the Berserker gives me great immunities in Rage, but no Fighter HLAs, and the Blade needs to be buffed or he's useless.

LMK what works the best in a powergaming sense.

TIA

i would go with blade just for fun

I'd say gnome. you'll want defensive spells in 8th level instead of adhw, but 2 time stops with a f/m is an overkill, even without gww. Use with ravager halberd if you have an unmodded game. MUCH more affective than chaining adhws