I’ve done insanity and max 30. I prefer max 30 because it’s shorter and has a modifier – I did the original afterwards and if I couldn’t do moves, I used the modifications I’d learned. It’s harder than T25, a whole new level but it’s really effective.
If you’ve done T25 before and are strong / confident then Max 30 is amazing. I preferred it over insanity. Max 30 is far more intense than T25 so it will depend on your own fitness level. I’d recommend doing T25 first before venturing to Max 30 or Insanity. Use it as a stepping stone.
I completed insanity long ago. I remember the workouts being hard, but I was so proud when I completed the program. The workouts are longer, but you do get some breaks. I’d think you’d see results either way. You’ll just have to decide if you want 25 min workouts or have more time to devote to insanity.