Finally! Been waiting for something like this. Now, as far as looks go, here's my list:
Alaskan Village: Little bit of bias here because my build team made this map, but I'll post it anyhow. The builds are themed properly with enough variation in the aesthetics to make it interesting. It's not
just a factory city, it's a factory set in Alaska that has taken over the rural fishing villages. Terraforming was done in WorldPainter and as such is very clean and easy to PVP on. Plus, modern just works well with everything PVP hah.
Fallen Empire: A map I really wish they redid the tiering on so it would become popular again. I don't like the revamp but I loved playing 48 player maps on this back in the day. The cities are very full and you're just
so immersed in the theme. Not many maps accomplish this; they're often just a building here and there and they call it a "theme". Not so with this map!
Mockingjay: Sure, this map is very new but it's got loads of room to PVP in and
they used a custom tree pack! Horray, most people don't even know what those are, but basically they used super huge custom made trees to make the map look more epic. Depth is appropriate for the theme and interiors are all done. A little reminiscent of SG 4 Revamped however, so dock a few points on originality in block pallettes.
Teweran SG2: Always holding a soft spot in my heart. I agree completely with
SuperxAndrew that Teweran is the best thing that could happen to MCSG. This map doesn't show all his skill but his knowledge of depth and story were unsurpassed.
La Brocanterie: I'm surprised nobody has placed this. If you look at overhead renders of this map it blows your mind. People may complain that there is no "theme" but I would disagree in that
this theme involves all themes. Normally when this is done it looks terrible, but with the size of the map and the block pallettes of the base of the map set your mind up for the craziness that is La Brocanterie.