Recommend you check out dungeon world. It's fairly rules light, it's got a d&d feel, and you have all your "regular" d&d style classes.
It's a "powered by the apocalypse" system, which means it utilizes a 2d6 rolling mechanic that leans towards success.
That is, generally speaking, it's a graded scale. Roll 2d6, add modifiers. under 6 is failure, 7-9 is a "medium" success, and 10+ is a "great" success. It leans towards success because the average of 2d6 before modifiers is 7, the lowest success number.
One thing that might trip you up running it (I know it did me), is that enemies don't get a "turn". The enemy turn is essentially the player's failures. You go in to attack and roll a 6? The enemy parries your attack and counters you.