I started out using Personal Ancestral File (PAF), switched to FTM2008-2011, then made the switch to Roots Magic.
Depending on what I want to do I switch between PAF and Roots Magic.
I am working with someone else on a one name line, I use PAF because I can use it at work and because the file is much easier to transfer between programs. I also like that I can quickly enter names and data since I can use the keyboard for most everything. Since this study is mostly names and vitals it's much much quicker using PAF.
For my own personal tree, of which I use a lot of different sources and many different facts. I also like the way that Roots Magic creates books and other reports. Roots Magic can also be put on a memory stick and taken with you which is also a nice plus.