Family Historian is UK developed. Roots Magic appears to be American. Depending on where your research is, and what features you are looking for, one may suit you better than the other.
I have an old version of FamilyHistorian which I found good but complex. There are user help groups though, and help here if needed. I don’t have experience with Roots Magic.
Like Erato, I like a simple program so use the free version of Tribal Pages these days which suits me well enough. I use my iPad exclusively and my Family Historian is on the PC, hence Tribal Pages is my preferred tree maker.