Well... it's nearly impossible to truly get rid of the possibility of min/maxing in any game system because it's simply the nature of us as people and gamers to want to make characters that are really good at something, and if a game allows us to manipulate it in some way than a lot of players will take advantage of that within the game's mechanisms and succeed no matter what you try to do.
This is not any particular game's fault. It's a player thing in combination of the social dynamic and social contract implied through the group coming together to play a game that everybody wants to play while agreeing to play the game that was talked about.
Another facet not considered at all is the fact that different players get their fun in rpgs in different ways. There are 8 Kinds of Fun that all of us get from our games, and while all of us get fun in the 8 ways, the order and preferences in which we find our fun is always different.
Because we are all different, it's virtually impossible to design a traditional game system that deals with all 8 kinds of fun and there's no way to truly get rid of min/maxing.
The games that have come the closest, though, are these games and these are the ones you should look at as inspiration (and this is of course not a finite list... just the ones I can think of atm):
Apocalypse World (and any *World Engine game) - Monsterhearts, Dungeon World, Monster of the Week, etc.
Smallville, Marvel Heroic, Firefly and really any Cortex Plus game.
Burning Wheel
Fate Core and Atomic Robo
DramaSystem by Pelgrane (who did 13th Age)
Mutant City Blues, Nights Black Agents and any Gumshoe game
Numenera and Cypher System
FFG Star Wars: Edge of the Empire/Age of Rebellion/Force & Destiny
Now all of these can be manipulated to an extent, all of them do have built in game balances that do prevent real min/maxing that can happen in a lot of other games. The only ones that are class like games are the *World Engine games, Numenera and the FFG Star Wars games, and in these games the 'classes' are loose and customizable yet they are really focused and limited in their overall power potential equally among all of them so no one 'class' outshines any other. They also don't have exactly traditional game mechanisms in them.
Apocalypse World has a 2d6+modifier roll that is then checked on a spectrum of possible results that result in a wide variety of possible outcomes. Numenera allows the players to choose to spend their own utility to make some results easier to determine while using a simple d20 roll to determine success. Both of these are also player roll only games and the GM never does any dice rolling. Star Wars uses customized dice and a unique dice pool system that allows for a wide variety of results in a single roll that focuses not on combat but the narrative exploration of every scene and provides players a wide scope of interpretation.
The thing with all these games is that they are all virtually simple. Easy dice rolls, easy to use and play and lots of simple choices to make. The more mechanisms and options you put into a game, the more the players will have to focus and optimize to make a character that can work. It's ironic really.
And in the case of Cortex Plus, these games are impossible to break and you can't min/max in them. You can try, but they are designed very well. Just check out Firefly and see that even Jayne is a well rounded character.
edit: I forgot a game you should check out. Tenra Bansho Zero is a rpg that was originally a Japanese rpg that got a really awesome English translation that has a really solid dice pool system that uses character ideas similar to Fate Aspects and the game is really amazing. How I described it here as far as it's system goes does not do it justice. It's truly an amazing game and as far as games with dice pools this is probably the best dice pool game ever designed.