If humanity were to colonize space it would make sense to make a choice of what kind of people to bring. This is reflected in the 'Choose Colonists' screen, where there are several options:
+2 Science in every city
+2 Food in every city
+2 Production in every city
Build colonists and explorers twice as fast 
It is debatable whether or not one should double-down here (for instance PAC that already has production and improvement bonuses, which can be increased by selecting Engineers). However, such a choice could potentially make your civ vulnerable in other areas. A safer choice as a beginner is to select colonists that will provide something you might struggle to get otherwise.
Scientists: Straight-up science boost, and lets you get those early techs a bit faster.
Refugees: Also quite simple, as it will boost your growth in all cities. However, as with PAU above, you need to mind your Health a bit more.
Aristocrats: Provides a boost to Energy, which is the currency in the game. It is used to support buildings, improvements and units, but can be used to purchase things instead of producing them. Good for a commerce game.
Engineers: Another straightforward option, as production takes place a bit faster.
Artists: A culture boost that starts up your progress towards Virtues from the get-go.
- ↑ 1.0 1.1 Note: In the December 2014 patch the +1 Health bonuses from Artists and Aristocrats were removed, but their Energy and Culture outputs were increased by one.
- ↑ 2.0 2.1 Pioneers and Mercenaries are only available as unlockables playing Sid Meier's Starships
|Civilization: Beyond Earth [Edit]|
|Games: Base Beyond Earth • Rising Tide • Starships‡|
† Introduced in Rising Tide • ‡ Spin off game based in the same fictional universe