For years, FSI was the only game in town. That alone caused them, IMHO, to become a little lax in their training since you only had basically one choice in simulator training.
Along comes SimuFlite and FSI really started rethinking their game plan. I used SimuFlite for six years and was very pleased. When you went to training you weren't buried with resumes from instructors looking for work.
Today, FSI is at the top of their game...again attributed to competition. Classrooms are being updated with computers and state-of-the-art training aids, software, digital CPTs and simulators.
I think all three previously mentioned will provide acceptable training. You just need to try all three and pick which one serves your needs the best. Another thing to consider is what sims are available. FSI usually gets first crack at new sims. SimuFlite follows close behind. SimCom only has a few available. For example, for us to train on the Ultra, which SimCom offers this course, we'd have to train in a Citation II with steam guages and do a differences. In my opinion, even though I'm saving a few bucks, I want to train in what I fly. We can talk about EFIS failures/malfunctions all day long, but I want to be able to train with them as well. Also, there is enough performance differences between the two that you can't accurately portray the Ultra using a II (for example).
2000Flyer