Here are some suggestions to give a small makeover to the old or outdated factions.
Scaven- the unique traits for lords and heroes like sharp teeth. frankly these should either be removed or buffed. im not sure on the purpose of them but they are effectively nerfs of existing traits. except for the sneaky one. that is great and should stay. but if the purpose of these lesser traits was to be that...lesser, at least make it obvious. like the high elves traits when you dont have enough of their resource.
Some of the older LL's talents are extremely bland or just bad. Skrolk for example, i'd like to see more talents to improve the plague units, and not just by making them a bit cheaper (buffing plague monks) or the other lords that improve some of the melee. For scaven melee units have always been low on the totem pole and i'd really like to see the lords that give some bonuses on those melee make them into a viable option (eshin triads, plaugemonks, gutter runner or whatever anti-infantry melee unit). Another is the beastman that starts near Khorne, cant remember his name, but he has a talent that says it increases missile damage. not army missile damage. just missile damage. meaning it only applies to him, but he has ZERO ranged attacks. its a dead talent.
Personally i really enjoy lords that buff specific units. not as much when its bottom tier'd units like arenessa, but if they are worthwhile then its not so bad.
Staying on the topic of vampire coast. the legendary lords are not able to move while in ambush stance while the new lords can. Seems this wasn't ported correctly. Going back to arenessa i think its fine that she really buffs the sartosan militia but i think she has like 4-5 talents that buff individual stats, and not even the ranged aspects for the ranged unit. but with so many other important and desirable talents to pick and with all of those talents being needed to make them barely-equal to a mid-tier unit, i'd like to see some condensing of those talents. with addition to improving the ranged unit making it less of a tax to choose those talents and using a bottom tier unit a bit more worth it. As for the Artillery, for the race as a whole its pretty weak. because the reload is so slow they are pretty bad. i'd like to see a reload reduction added to the red line.