I usually do a lattice because I like the way it looks and I have never quite mastered the art of not leaving a large void under the solid top. I make cherry pie most often and this is what I do.
I put fresh or frozen cherries in a small steamer with a couple of tablespoons of water in the bottom.
I cook that on very low heat until the cherries soften and I have a good amount of juice in the bottom of the steamer 1-1 1/2 cups.
I adjust the flavor of the juice by adding sugar, salt, acid until it tastes perfect.
I measure the amount of liquid and add the proper amount of cornstarch then I cook the it until it begins to turn clear.
It will thicken a bit and I can tell whether the balance is correct by how much it thickens.
Then I fold the cherries gently into the cooked juice and put it hot into a prebaked pie shell.
This method also takes some of the guess work out of apple pies. I have made apple pies with home grown fruit many times and it is difficult to predict when the apple slices will soften properly. By precooking in the steamer you can judge when the apple is beginning to soften.