At level 35 my kingdom controls 20% of the map and my lord stats are 35s 32a 34i 38c, at the very least you can consider mid-range stats to be double vanilla, with some characters like giants going as high as 50+ strength. But if you want to know some levels to shoot for there are some.
power draw (agi X3) - each point helps, but at 4-6-8 your options improve a lot, every npc on my team rushed to six. (18 agi)
riding (agi X3) can't ride any warhorses until 5, can't ride the perisno warhorse until 8, each point helps your options but those count most.
early game armor - elven armor has low strength requirements and good ac for low strength, but starts to be surpassed when you can start wearing heavier plate from other factions around strength 22. -- late game bows however come mostly from elven faction.
shield skill - only need 4 to use the best shields, 3 will let you use a lot of shields that are good, ie-elven
related- weapons master- you are going to be fighting a lot, the sooner your companions have a decent weapons master skill 5+ the sooner they can be that badass elite immortal troop group they are meant to be.
on stats themselves -- talking to lords who you have max/near max faction with will give you a small chance to improve your stats, also stats just go up passively by using them, even for NPCS for example my surgeon-first-aid-guy with skill 10/10 went from 30 int (early game rushed stat) to 38 (mid-game) intelligence. I didn't put any points into that after 30.