1. Replace the scripting system with an "orders" system, allowing you to issue orders to one or more party members quickly on the fly through something like a radial menu. Can select a party member and select one or more enemies to attack, an ally to heal if they fall below X% health, tank these enemies, protect these allies (tank or crowd control enemies off them), coordinate with (attack the target they're attacking, exploit vulnerabilities they set up), crowd control these enemies, mark certain targets as priority targets, so if a party member has nothing better to do, they'll switch to attacking one of the priority targets.
2. Improve the talent and skills system so that most classes get access to most moves early on (giving you a chance to play around with them), and later on you unlock upgrades and modifiers (similar to runes in Diablo 3, you can only have a finite number or they have drawbacks, increased power but more cost and longer cooldown, as such having a large number of upgrades doesn't necessarily make you overpowered). Can save different variants of moves to your abilities wheel, allowing for you to have fewer moves, but keep the same amount of combat versatility. Able to get a much larger proportion of the total available upgrades, and create more flexible characters (ie a rogue that is capable at both archery and melee, a mage that is capable at healing and damage/CC), allowing you to adjust party combat roles as needed (if a companion leaves, dies, if you prefer the personality of certain companions or if it's better for story if one or two come along that aren't part of your regular group, also saves you having to put up with a character you can't stand just because he's one of two mages and the only one that can heal... guess who I'm talking about).
3. MUCH more varied class customisation options. You can make your characters into a hybrid (turn a Rogue or Warrior into a Rogure/Warrior hybrid), can create Battlemages, Rangers, Beastmasters, Rogue/Mage hybrids, with a lot more player control over the specialisations within those classes (ie a Battlemage can focus on offensive magic, offensive melee combat, defensive melee combat, healing etc). I want to make a badass swordsman with a fast 2h blade in medium armour that can heal and use force magic.
4. All classes able to fill all party roles, rogues and warriors can heal, mages and rogues can tank. Also classes can have methods to self heal and improve their survivability, but this usually makes them less effective than if they were coordinating with a specialised healer and tank (ie less DPS).
5. Make the talent system MUCH more intuitive. I want to be able to look at the talent trees and say "I want to increase my survivability" and know almost immediately what talents are best to pick. Probably remove the attributes system and include those choices (more damage vs more energy vs more survivability) into the talent trees and moves/equipment you select (ie you have certain moves that boost your defense at the expense of DPS if you want to focus on survivability in a tough fight).
Runners up:
- Mage politics, particularly with a wide variety of options, such as various approaches to the Aequitarian or Isolationist principles. Can promote reform of concepts like apostasy (ie may make it that all mages are expected to undergo a certain degree of training and evaluation to ensure they are not a danger to themselves or others, but this does not require them to be forcefully removed from their family).
- Meaningful choices. For example in DA 2 I would've loved for Kirkwall to either undergo a complete social collapse (anarchy in the streets, mass unemployment etc), or be ushered into a golden age (prosperity, housing development, city beautification such as gardens) based on events. These choices could include needing to do several things at the same time, if you've built up friends and allies, you can split up and try to do both, otherwise you have to choose.
- A full craft system (able to choose a design for a sword, shield, chestplate you like, gather the materials, choose what stat buffs you want, can upgrade or alter the stats by gathering more supplies, can customise its appearance with different coloured minerals, finishes, decals, insignias, secondary elements like fabric). Could be able to break down loot to make these items (so you can have you and your allies have the ACTUAL equipment you want in terms of item skin and stats, and save you having to carry around large amounts of average gear because you "might need it" if you decide your mage needs more mana regen, and save you having to sit there for over an hour after each major quest manually switching out party members to compare your new loot to existing gear, and storing "maybes" in the storage chest).
- Can develop factions, with similar gameplay elements to building your stronghold in Awakening (ie help a faction build up a fort, recruit, get a smith, improve the quality of their equipment) and they can play a role later in the story.
- More political intrigue and power games (a la Game of Thrones), you can try to "play the game", or consider it too dirty a game and try to avoid it. These can include putting you in tough positions (ie finding out a political ally is a criminal, do you cover for him and risk being exposed, or expose him and lose an ally).
- Nudity, The Witcher 2 added it and the world didn't explode. Could also include "sexual scenes" (as distinct from sex scenes, ie characters engaging in kissing, touching, flirting etc without actually having sex, example, the scene with Idunna, especially if you two were alone and she was dressed in revealing clothes, she touches you etc).
- Non-party member romances, particularly ones that aren't emotionally damaged pirates or insane obsessed blood mages, coming home after a hard quest to someone like Lady Elegant would've been awesome.
- More romantic interactions (ie can wake up next to your partner, have pillow talk, hug, kiss, take time to have a drink/meal with them, can have sex with them more than once, different places, different emotional contexts).
- You have MUCH more control over how a romance develops (ie if its casual or serious or various shades in between, you aren't forced to choose between saying "I love you" or dumping them).
- MUCH less emo factor.
- Clear and different motivations for the protagonist (ie if you make it clear you're after power or trying to do good in the world, NPCs will react differently to you, including if they want your help, they'll give you a different sales pitch).
- Ways to earn more money (investments, repeatable random quests that fill a random dungeon with enemies), and more you can do with money (upgrade your equipment, customise your house, make investments, help certain factions grow, donate to certain initiatives such as those helping the poor).
- Make some of the prostitutes/courtesans, madams more interesting (ie some have dialogue, backstories and side quests).
- More varied female proportions (watching Isabela doing backflips I half expected those puppies to do in her back).
- I liked the DAO models for darkspawn better.
- Can you make it possible to self heal as a Warrior without being a Reaver. If I'm roleplaying as a noble Warrior but like survivability that puts me in a bind.
- Would be nice if you include the ability to have more than one charge of an ability at once (ie you can cast two fireballs in rapid succession, and both cooldowns will recharge over time).
- Could have it that some moves build up charge that other moves consume (so a warriors charge makes your next mighty blow within 6 seconds do more damage and cost 50% less energy).
- May make it that your companions have lives of their own (they frequently go off to do their own thing, rather than following you into the deeproads for several weeks because you ask nicely).