For power out of the hole I like to ATG pause squats, low box squats and halting squats. When i started lifting I had particularly low strength out of the hole as compared to the top half of my squat.
I front squat (oly style) and I'm a BIG advocate for it. Look at how many PLers these days are putting it in their routines. I've been doing them for years all the way back when I first started them back as an Olympic weightlifter. I do them b/c they have a GREAT deal of carryover to conventional pulls.
If you are having a problem hitting depth it could be a mobility issue if you're trying to squat with a wide stance. You can alleviate this by ducking your feet but you want to address the issue by working on increasing your mobility. Chad Wesley Smith and Kelly Starett (sp) both have a BUNCH of vids that address how to attack this issue.
If someone wants to build strength out of the "hole" than add 2 movements in your routine: Anderson Squats and Paused Back Squats.