Here's what I've been thinking for races in KotC 2:
Human: one extra feat at the beginning. Advantage: Extra Feat.
Half-Orc: DEX -2, STR +2, Toughness. Advantage: High Strength.
Dwarf: CON +2, WIS -2, Speed 20, +2 Dodge bonus to AC against melee attacks from large creatures or bigger. Advantage: High Hit Points.
High Elf: DEX +2, CON -2, immunity to sleep. Advantage: High Dexterity.
Grey Elf: STR -2, DEX +2, CON -2, INT +2, immunity to sleep. Advantage: High Intelligence.
Halfling: STR -2, DEX +2, Size Small (less damage from weapons, +1 size bonus to all attack rolls and to AC), Speed 20, +2 bonus to all saving throws. Advantage: High Saving Throws.
Kobold: STR -2, DEX +2, CON -2, Size Small, Speed 30, +2 Natural Armor bonus to AC. Advantage: High Armor Class.
Thri-Kreen: STR -2, DEX +2, INT -2, WIS +2, CHA -2, Speed 40, Can’t wear armour, Can wield up to 4 weapons, +3 Natural Armor bonus to AC, Paralyzing bite from level 7. Advantage: Number of Attacks.
Half-Giant: STR +4, DEX -6, CON +2, INT -4, WIS -4, CHA -2. Size Large (more damage from weapons, -1 size bonus to all attack rolls and to AC), Speed 20. Advantage: High Damage.
Some issues that could be discussed:
Are the half-giant and thri-kreen irremediably unbalanced?
Should thri-kreens be prohibited from wearing cloaks, rings, helms, boots, belts and bracers too?
Is kobold a good idea for a character class?
Should halflings have a wisdom bonus?