For part of a project I'm starting, I want to use a 9-axis IMU for Absolute Orientation. I want to go with MPU-9250, but I don't know if there is better choice then that. Is there a current popular choice when it comes to these sensors nowadays?
The MPU-9250 was discontinued a couple of years ago, and the replacements generally work better. Consider its successor, the ICM-20948, or the LSM9DS1, both available from your favorite hobby supplier, with solid Arduino libraries and AHRS code.