For researching, conceptualizing, evaluating, designing, and communicating I prefer to use a VIsual THinking ENvironment or #VITHEN.
There are three tools I use most on my Mac TOGETHER as a visual thinking environment. My preferred programs are iMindMap, Scapple, and Big Hairy Goal. I would rank them 1, 2.5, and 2.5 respectively.
Note that I do not use these three programs alone and on many project use iMindMap plus (Scapple or Big Hairy Goal). Combined these three programs provide an excellent VITHEN. If you only want to work with one program, use iMindMap, the premier and most comprehensive product in this space.
And, yes I coined the term VITHEN.