Well, I like and use Sky Safari on my phone, sorry George
I like how you use the phone to point at points of light in the sky and it lets you know what star/planet it is. The GPS feature is useful for knowing where you are (yes, you can get that from other apps, but it's all in the one which is handy). I have the "Plus" version which can control my WiFi enabled scope remotely, it's also really handy for finding stars to use as markers when you are searching for other stars (eg G2V for calibration purposes).
Most of this stuff you can probably find on the PC version of Stellarium or other PC apps, but when I've got my computer setup for recording videos/photos, I like having a second screen available for checking stuff.
I've only started this recently, so any app that helps me find what I'm looking for is useful.
Andrew