Always a topic for discussion and debate. Opinions vary widely. And the so-called "club experts" always have "the answer."
I think most shooters who improve their game over time tend to gravitate towards tighter chokes than what they started with.
But I-MOD is a good choice, as long as you check to make sure it throws patterns that you'd expect from an I-MOD.
Further back (25-27), FULL is probably a better choice. But again, you don't know until you check to see what patterns it actually throws, and eyeballing a grease board doesn't cut it, in my opinion.
It helps to actually test with a program like Shotgun Insight to find the real pattern percentage.