I hold Izotope in high regard and believe that they make some of the highest quality plugins on the market. If I had an abundance of Izotope plugins at my disposal, I would reach for them as often as possible.  That being said, as a basic concept, I think it is a good idea to try and master a few specific plugins before doing excessive amounts of experimentation with a bunch of other ones. This will get you working more efficiently and go a long way in helping you develop that coveted "signature sound" that every artist wants to find.