The Sig Kadet Senior is arguably the most successful trainer in RC history and is a delightful airplane capable of far more than just training. They work well in the kit version without ailerons or modified with. There also is an arf version with less dihedral and ailerons.

Beyond flight training they are ideal:

Night flyers
cross country airplanes
float planes
multi engine conversions (two and more engines)

Repairs are very simple with the stick structure and the Senior has been bashed by someone, somewhere in every conceivable configuration possible even tailless.

If It sounds like its and old favorite of mine then that is true, Here is my eighteen year old one: