I have to agree with @Benjamin Hayward @Grumpy Gnome, so many games exist in so many sizes and genres and styles because they all appeal to at least some audience. Or in other words what makes a wargame "good" for one player, may not make it good for another.
For myself, I want the game to be decided by maneuver and massing of fires, etc. In other words tactics. I don't want the game won by combining character bubbles for re-rolls and coming up with cool "strategy" card combos (If I wanted to play Ug Gi Go I would). Looking at you current 40K.
An example of this. I'm moving away from Saga to Ravenfeast or similar because I want to "fight" my troops. Not a game board. (All Saga warband have a unique game board with different abilities on it. It's kinda neat, but that's more the game than the moving about of troops. Your mileage may vary).
Saga
http://www.ravenfeast.com/
(Ravenfeast. All rules and expansions are free!)
Like Grumpy Gnome I prefer the miniatures represent 1 to 1. This generally means I will only ever play company sized actions and I'm generally OK with that.
I am however consequently interested in 6mm sci-fi and 12ish (whatever size the Warlord Epic Napoleonic miniatures are) in order to play larger force size games.
I will say what makes a good game is mysterious. I really enjoy playing "B-17 Queen of the Skies." So much so I got the reimagined "Target for Today." But I honestly can't tell you where the "game" is. It's a solitary "simulator" with very few decisions to make. None the less it enjoys a strong following all these years later. (There's a free printable B-25 in the Pacific game floating around out there somewhere if you want to give similar a try.) (I've always wanted to do a 40K Marauder bomber version as well..... the problem largely being it's a sh*t load of work and I'm lazy/have a job.) Note: B-17 is not a miniatures game per say. Although it could be with 1/144 models and it would be awesome.
B-17 Queen of the Skies
EDIT: Here is the B-25 game. Look under "Files" for the printable rules, etc.
B-25 game