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).
(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.