I prefered overgrown, it had some medium to close combat, unlike in cliffside, where it's either sniper from one side of the map to the other, or getting blitzed with an MP40 around the side bits and the building in the middle
I personally prefer cliffside because I thought overgrown didn't really make a good map, it was too big with so many buildings and trick jumps for people to hide in, whereas in cliffside you got one or two buildings, some decent cover and good strips for snipers and SMG's