Maybe there should be a list of maps recommended to first time players new to CS. The reason I suggest this is there are over 1000 maps in CS. That number alone, plus the large volume of mediocre maps could sour a new player off the whole CS experience before they become used to the system and learn to navigate it.
Here are some hypothetical rules for such a hypothetical list:
1) One play this first recommendation per person.
2) Recommendation must be appropriate for new players.
3) Your description of your recommendation must be kept short.
4) No PAC maps. There is another list for that.
5) No recommending your own map.
Example recommendation:
Map #237: Emergence
Beautiful map where you fight an unusual enemy that rises from the deep. Very cool.
Ideally no maps with CRPL should be recommended, except maybe an introductory tutorial to it.
(http://knucklecracker.com/forums/index.php?action=dlattach;topic=18216.0;attach=19470;image)
The few early maps by Michionlion are really good for example the twisted islands #35.
Flip Flop Fly by Flabot one of the first maps with flip emitters. #65
edurans maps especially the Asteroid belt #82
For some fun CRPL that is not regular gameplay see PlatformerV2 by stewbasic #146
And if someone didn't play them then the Pass the Map series is fun but that's for a player that can handle CRPL.
If I had to make one recommendation then the Asteroid belt by eduran is the best of the ones there. While there is some CRPL it's kept simple with a lot of visual indication of what's going on. So map nr #82.
Pass the map 5. It is a good map to learn how to deal with different enemies. That no crpl rule was a good idea. Other pass the map maps are full of crpl.