If you don't mind being shackled to Headband of Intellect, then 6 Eldritch Knight/6 Wizard can work.
6 EK for the extra attack, bonus feat and a bit of spell slot progress. 6 Wizard for extra spell slots, more spells and some subclass bonuses. Abjuration School can work well for continuing the Fighter style "Front line tank" and can be seriously strong (Heavy Armour + Heavy Armour Mastery + Arcane Ward = Good luck taking damage at all, ever. Heck toss on Warding Bond and be practically invulnerable)
Though you can go something like Divination for more support via Portent too.
While all this still is thematic, given Githyanki do like to mix martial and magic combat.
This is actually interesting! I once tried a 6/6 split with the headband, went for divination and battle master, the idea was to guarantee the effects for each of the special attacks by using portent. I also tried to spice it up with stacking damage riders on a main hand weapon and a ranged weapon, you can have fire/acid/lightning/psychic/radiant/force/posion at the same time. That can guarantee you a damage based prophecy fulfillment from a single weapon attack, sometimes even two prophecies.
Right now though I've already planned for a wizard/rogue/fighter AA Astarion in the party, so I would want to diversify my party with a class that I don't yet have.
I have just one idea of going 1 fighter, 11 ranger hunter with colossus slayer, multiattack defense and defensive duelist (Laezel has exactly the minimum of 13 DEX). Go for heavy armor and finesse two-handers. Hunter feels natural for a Githyanki, I think. Have you tried defensive duelist, is it bad or OK?
