Meta decks atm based on podcasts and events that I've witnessed:
Skywalker Twins Leia eTroopers
then optional mix of Force Users and Alliance Smugglers in any of the archetypes above. Rebels really have the biggest wiggle room for modifications as there are known archetypes but no clear concrete list to each. Imperial: Troopers Spam (Spy or non spy variants)
Grand Inquisitor Vader's Fist type list
Sorin with HK Assassin Droids
Probably the most commonly seen faction as EStormtroopers are just so cost efficient for what they do.
Mercenaries (or Scum):
Bantha - Tusken Warrior Jundland Terror
Bossk Trandos Strain list
then HK Assassin Droids depending on the player (usually buffed by Gideon and C3PO)
Both good solid lists for wrecking the battlefield and killing all that stand in your way.
FFG can approach the overcosted problem 3 ways : 1.) Make new cards that will overshadow older incarnations of the characters (which I suppose is the running trend) 2.) Errata, but this is probably a sad choice to do.
3.) Increase the max deployment value to maybe 50 instead of 40. So Vader taking up 2/5 instead of 1/2 of your list gives you enough wiggle room to add more bodies in your list, and I don't believe the balance of the game to be broken too much.