Hello concerning your question about whats better for crown control it would have to be the illusionist for the fact being they have 2 seperate mezzes and a group mezz and also have a proc you can cast on a person so they do damage with each cast.they also have a pet that does rooting and mezzing called the personae and changes names over diferent lvls.
The coercer has the charm ability which comes in handy for adds that are of heroic status releiving pressure off the group. They also have an annoyance demeanor which helps the tank keep aggro and also an attack buff which helps the tank do more damage over time producing more aggro. they also have a mezz and group mezz just like the illusionist but do lack the extra mezz given to an illusionist so i leave the choice to you given the facts you now have