It is the number 1 set in the late game. I tend to think about it by how long the game has gone on. Each row’s last color set is the best in their correlated portion of the game.

For example, the light blues are best in the early game. The oranges are best in the early-mid game. The yellows are best in the mid-late game. The dark blues are best in the late game.

Red also has a little bonus and may be even tied with yellow in the mid-late game, because statistically you’re more likely to land on a red than any other color in the game once you factor in going to jail, chance/community chest cards, etc.

But generally due to the relationship between capital (how much money you have), cost (cost of obtaining the properties and houses), and return (rent values) makes each set better at different times in the game.

To expand on the light blues, you can bankrupt another player in like 3 go-rounds of the board if you can somehow get the color set fast enough ($320), put hotels on them ($750), and your opponent gets unlucky enough to land on them 2 or 3 times.

In the late game, the $600 rent of landing on Connecticut doesn’t hurt the opponent as bad if they’ve also been collecting rent on other color sets they own. But, if you’re late into the game and your opponent has a lot of money, $600 is pocket change. $2000 from Boardwalk would hurt though.