I have the Oakley photochromic lenses, prizm road, and the prizm trail.
I live in Portland, Oregon, and commute year round. For my commutes, I use the photochromic almost exclusively. The only exceptions are in the summer when it is reliably sunny, sunrise is before 6AM and sets at 9PM - Prizm Road for those days.
Both the Prizm Trail and Photochromic are great for cloudy conditions. I primarily use the Prizm Trail if I am going to spend a lot of time off road, or a lot of time in canopy, where I frequently go from sun to shade. I also use them if I am going to be in canopy on a cloudy day.
The Photochromic is what I take if I am leaving before dark, returning after dark, or I am going to be in partly sunny conditions. The photochromic lens goes from nearly clear to a light grey. You can use them in the dark, or in full sun. While a dark polarized lens (or Prizm Road) is more comfortable in full sun, the Photochromic is just dark enough to be acceptable for me. There are a couple of downsides of the Photochromic. The first is that they are relatively slow to change from light to dark and vice-versa. They are not going to adjust quickly when riding in and out of canopy in bright sun. They adjust to what I would call the average condition. I actually like this.
The second downside to the photochromic is that they are completely useless for driving. They adjust to darkness with UV light, and automotive glass removes most UV light. Even in bright sun, they will not darken if you are in the car.
If I could only have one lens for riding in my climate (300 cloudy days per year), it would be the photochromic. While I love my Prism trail for gravel rides and mountain biking, and the Prism Roam for road rides on one of the 60 sunny days per year, the photochromic is the only one that I can ride comfortably in the dark, but still be comfortable in full sun.