the trees are normal size, about 5 meters as you said. those 20 meters or abnormal large trees i dont see any.
SC4 graphics look cool from a distance, so does Cities XL( cities xl maybe a bit better, because of lighting)
Up close SC4 is rather large pixels 1cm x 1cm in 2d, and looks horrible.
Up close Cities XL, very high resolution, 3d and very nice lightning
You agree that Cities XL graphics looks nice, but you dont like it because of cartoonish graphics. I guess that your definition of cartoonish graphics is bold forms, stuff rendered with AA and lightning. and that pretty much fits on Cities XL. So SC4 looks realistic, straight edges, pixelated and semi 3d. Now whats most realistic? SC4 is most realistic if u dont wear your glasses, because everything looks like its a bit pixelated, but blurred. in SC4 its just pixelated. the only 2d thing I ever saw in real life is a perfect ball. the only straight edges that I see in real life... well I never saw any.. everything in real life seems to have some kind of shadowz before it fades into another thing. And shadows(and lightning ) is what Cities XL has. in real life everything is "rendered" in 3d. Oh im sorry theres also a 4th dimension, but human mid isnt advanced enough to "see" it, so 3d is most realistic for us. Our eyes capture everything in real life in 999999999999 pixels x 9999999999999 pixels with 24 FPS . Now I dont know whats the resolution of simcity 4 in close up i guess its something about 600 x 400.