I've been using BigWigs since... I don't even know. I started using it some time before 2.0. I think I went from CT_RA to ... XRP? I don't remember the name of the boss mod. The one everyone was using during Naxx progression because it was so easy to write plugins for. Then after a short phase with that I went to BigWigs since it had all the boss data I needed by then.
I haven't had a reason to change since.