I am asking this question in terms of size, memory usage and ability to use in forms project. because my experience with most of the tools available for forms is very disappointing.
1) First started with xamarin insights. It makes your start up time super slow ads 2-3 secs extra. Once I uninstalled it my app size reduced 6 mb. it.
2) HockeyApp, they dont have any support for xamarin forms. basically you cant catch any tracked exception in your xamarin forms app. basically they are telling you use try catch do nothing 
I think that last option leaves me is mobile center. But I cant find any xamarin forms exception tracking information. does anybody know how to handle exceptions in forms application using mobile center