As the CFI at our club, I get to fly both -- frequently. Both are very good trainers, although quite different in concept.

The Alpha is a well-made standard trainer that flies beautifully. If you are a natural pilot, or a better than average student, it will work very well for you, possibly at marginally lower cost than the Nexstar, although, depending on your choice of power, it can cost more than the Nexstar. With comparable power & in stock trim, the Alpha is marginally more agile than the Nexstar is without its training aids (chiefly due to the Alpha's shallower dihedral).

The Nexstar is a broad spectrum trainer that can handle students of virtually any skill level, or aptitude, and as an instructor I have seen consistently better student success rates with the Nexstar, compared to any other trainer flying at our field. It is NOT overpriced -- the flight sim alone is an incrediby usefull tool, & the add-on flight aids are NOT gimmicks. They work extremely well & are indeed essential to some students, but may be non-essential to others. The airframe is good looking and very tough, while the OS FXi engine is the real thing & fully usefull for high-performance applications (either in a Nexstar hot-rod, or in a different sport plane).

Following completion of training, both models can be easily hot-rodded, and both have essentially the same aerobatic potential. In this scenario the Nexstar holds a minor advantage, as it will accept larger powerplants more easily.