quilt calc is very good. I use it all the time. Especially when writing my own patterns. I also use EQ7. LOVE, LOVE, LOVE both of them.
I have 2 friends--one with quilt calc, the other with EQ6. They use neither. Why? They don't want to take the time to learn how to use them. But I don't think that's it. As a person whose worked with computers and a lot of users, I find there are some who get frustrated with manuals and don't want to read them. They'd rather be shown.
So my conclusion, is that if you don't mind reading and taking the time to learn the software, then these two will solve all your problems. And you'll find your work from size decisions to the actual quilt will be faster. However, if you're not up to that, these two are not for you.
My two friends from above use a phone app. I think it's QuiltFab.