So, I've had the privilege of using the HVX200, HVX200A, HPX170 & HPX171 and the HPX250.
By far the worst for picture quality and lens width is the HVX200. The A version is majorly updated with a wider lens offering much more depth to the fisheye itself.
The HPX170 AND 171 are by far the most user friendly cameras I've actually used just based on the weight. The vig is completely random between camera models and can't be helped. The 171 I used had perfect vig in all corners.
I predominantly used the HPX250 for the latest video I did, and it's true - the added width on the xtreme is absolutely outrageous, but so is the size and weight of the HPX250, but it is by far the best camera out of the bunch.
I'm currently using the HPX174 (unsure of what the "4" represents), but the quality is glorious throughout the HPX range.
The HPX250 has AVC filming formats, giving more depth and quality overall to the video itself, but the size and weight of the camera is an absolute back breaker when combined with an xtreme, rail support system and light if you're filming in low light.
Overall, I'd say use the HPX171, that seemed to be my most enjoyable camera.