If fungus gnats were the only problem you faced with Miracle Grow then you've been lucky. I've seen some horror stories. It's not a good idea to use anything with time released nutes.
Fox Farm Ocean Forrest is a solid all around soil. It's pH'd at 7.0 and you wont have to feed your girls for the first month.
If you're looking for a mild soil then Fox Farm Light Warrior is a good choice. Fox Farm also puts beneficial micro organisms into their soil to help with root development.
I recently bought Ferti-Lome which is a mild soil, I bought it for my clones and ended up with an unexpected guest. Something was in the soil & sprouted next to one of my clones. So from now on I'm a FF man, never had any problems with their soil.
Good luck, and may all your green girls become monsters.