I am sure that different people will have different opinions what is the best simulator. What you can do is to download a demo from http://rcflightsim.com and try ClearView RC flight simulator - there is free trial time. This simulator povides very realistic plane flight modeling and has many models to choose.
Many people like also how ClearView models the helis so it is good all around simulator in case you will want to try planes and helis as well.