I think interstellar colonists will be more interested in the number, variety, and positioning of asteroids in a target star system rather than caring about planets at all, with the possible exception of small gas giants for hydrogen collection. For further insights I recommend Isaac Arthur's excellent Youtube series, including an episode that specifically talks about this issue: https://www.youtube.com/watch?v=6VBCxWcAPXw

I think interstellar colonists will be more interested in the number, variety, and positioning of asteroids in a target star system rather than caring about planets at all, with the possible exception of small gas giants for hydrogen collection. For further insights I recommend Isaac Arthur's excellent Youtube series, including an episode that specifically talks about this issue: Life in a Space Colony, ep3: Early Interstellar Colonies

1. They have lived their whole lives in space and that's probably true of their parents and grandparents as well. People accustomed for generations to living aboard ship will likely view the lifestyle of living on a planet as akin to how most of us would view the Amish. I'm sure they are generally happy with their lifestyle, but I'm not going to do it myself. ("You grow your crops in DIRT? Actual dirt? And you eat real animals? And you go outside and expose yourself directly to the raw environment?")

2. Asteroids (or space stations built from them) can easily be moved, eventually forming a Dyson swarm. This is much more efficient assuming you want to collect most of your energy from solar power. And imagine how much more peace we would have if you could simply pack up your country and move it if you didn't like who you were living next to.

3. There is a LOT more living space. A planet can support a few billion inhabitants, a Dyson swarm can support trillions.

4. Asteroid mining is better than planetary mining. The reason we don't do it now is because of how hard it is to get there, and minor lifestyle inconveniences like not being able to breathe. But if you already are there, and have the equipment to survive, the resources available are far greater than what we have on Earth.

5. Earth-size planets have inconveniently large gravity wells, hampering space travel. These colonists are likely to want to continue to travel in space and constructing a massive gravity well just so you can climb up and down it is not helpful at all.

6. The colonists may have genetically engineered themselves to adapt to the space environment, for example adding radiation resistance or tolerance for low gravity. Regardless of cultural and lifestyle issues, they might find an actual planet not especially welcoming biologically, or at least not more so than their regular space environment.

7. Energy availability on a planet is bad. You have three plausible choices for energy: solar, fusion, and fission, and all of them favor asteroids or space stations. Solar collection is optimized by constructing a Dyson swarm, for maximum collection area. Fusion power requires lots of volatiles (likely hydrogen), which will be most easily found in either cometary ice or, secondarily, the atmospheres of gas giants, depending on how good your rockets are and how much mass the gas giants have. This requires lots of travel to the outer, or at least middle, solar system to collect it. The low gravity of asteroids simplifies the launching and landing (as well as less energy and time needed for travel due to starting farther away from the star in the first place). Finally, fission power requires lots of uranium, which needs to be mined, and mining is easier on the asteroids. And if you're using fission, disposing of the radioactive waste is a lot easier if you can just toss it out into space (although I would expect colonists at this technology level to be quite a bit better at recycling, or at least concentrating, the stuff than we are).

1. They have lived their whole lives in space and that's probably true of their parents and grandparents as well. People accustomed for generations to living aboard ship will likely view the lifestyle of living on a planet as akin to how most of us would view the Amish. I'm sure they are generally happy with their lifestyle, but I'm not going to do it myself. ("You grow your crops in DIRT? Actual dirt? And you eat real animals? And you go outside and expose yourself directly to the raw environment?")

2. Asteroids (or space stations built from them) can easily be moved, eventually forming a Dyson swarm. This is much more efficient and a Dyson swarm is largely the standard model nowadays for a K-2 civilization.

3. There is a LOT more living space. A planet can support a few billion inhabitants, a Dyson swarm can support trillions.

4. Asteroid mining is better than planetary mining. The reason we don't do it now is because of how hard it is to get there, and minor lifestyle inconveniences like not being able to breathe. But if you already are there, and have the equipment to survive, the resources available are far greater than what we have on Earth.

5. Earth-size planets have inconveniently large gravity wells, hampering space travel. These colonists are likely to want to continue to travel in space and constructing a massive gravity well just so you can climb up and down it is not helpful at all.

6. The colonists may have genetically engineered themselves to adapt to the space environment, for example adding radiation resistance or tolerance for low gravity. Regardless of cultural and lifestyle issues, they might find an actual planet not especially welcoming biologically, or at least not more so than their regular space environment.

7. Energy availability on a planet is bad. You have three plausible choices for energy: solar, fusion, and fission, and all of them favor asteroids or space stations. Solar collection is optimized by constructing a Dyson swarm, for maximum collection area. Fusion power requires lots of volatiles (likely hydrogen), which will be most easily found in either cometary ice or, secondarily, the atmospheres of gas giants, depending on how good your rockets are and how much mass the gas giants have. This requires lots of travel to the outer, or at least middle, solar system to collect it. The low gravity of asteroids simplifies the launching and landing (as well as less energy and time needed for travel due to starting farther away from the star in the first place). Finally, fission power requires lots of uranium, which needs to be mined, and mining is easier on the asteroids. And if you're using fission, disposing of the radioactive waste is a lot easier if you can just toss it out into space (although I would expect colonists at this technology level to be quite a bit better at recycling, or at least concentrating, the stuff than we are).

8. Planets have pollution problems that you just don't have on space stations. While simply throwing waste overboard is not necessarily suitable in general (because it is still in your orbit and sooner or later it will come around again and might hit you) you can recycle what you can and easily move most of your really troublesome garbage into a non-intersecting orbit. If some disaster contaminates an entire habitat, you can just build a replacement. Actually there would probably be so many habitats that the civilization as a whole would barely even notice a Chernobyl or Fukushima.

9. Politics are easier when you have millions of more or less independent but cooperating habitats. When your only practical choices for war are "we will stop trading with you" and "we will blow up your habitat, killing everyone" it is more advantageous to just pack up and move away or ignore neighbors you dislike, discouraging violence and war. It also means everyone can find a political system that suits them personally. I think it's unlikely that everyone in the colony fleet will want the same political system. Some might want a libertarian utopia, a communist utopia, a socialist utopia, a military dictatorship utopia, or any other form of utopia they can think of, and all of these systems, including many I can't think of, will likely exist. "Asteroidica, love it or leave it" becomes a real option and people can move to any of the thousands or millions of competing political and social systems.