What's Your Favorite Poker Software or App?

There are so many tools out there - trackers, solvers, and study Apps. Which one do you find most helpful?

Personally, I've been using Hold'em Manager for a long time and I never play without its tracker. For my ranges, I used to use Range Manager, but now I use Range Craft because it's free with many more features and a very nice interface. I also use GTO Wizard, but I only have its free version without a subscription