What kind of game do you want to play? What planet settings do you have? It depends on so much.
Personally, I like space to be spaceous, so even on the larger maps I don't mind having few players. Similarly, I tend not to play Tiny with more than a couple. Other people want early-game interaction, and to be able to meet dozens of new races and interact with all of them. A "suggested players" for either of us would be meaningless for the other.
And then, if you have Rare suns, planets and habitable, with abundant extreme, there just aren't enough planets for lots of races. But Abundant and few extreme, there are a lot more planets.
