I own Shphere, Sphere Competition and GTB.
I like sphere because the drivability is really great. It doesnt need fan and it doesnt go thermal shutdown. LRP BL motor is also great because you can replace the sensor harness if the insulator goes bad.
On the other hand, I hate Sphere's drag brake. It's just not there even when you select the highest drag brake.
If your driving style requires a lot of drag brake or if you're running pan car, choose GTB. If not, go for Sphere competition.
For your info, I sent both my GTB and Sphere back to Novak and LRP. The GTB has faulty temperature sensor and the LRP just melted on straight line. I think, both Novak and LRP need to find more robust system. Both systems are similar so that's why they either need to conduct more R&D or just totally leave the current layout for something very very different that will provide them breakthrough in term of reliability.
Up until now, I still think, brush motor is far more reliable if compared to Novak or LRP brushless.