Double south river exits was my only map requirement. I got the worst of the rest (blue airport, pears, cosmos), but I needed my symmetry.
I love pears and cosmos and blue airports so I'm glad the game has something for me. The only fruit I dislike is oranges since they are more tropical and I like deciduous forests.
As for my maps, I've reset so many times that I've had something like 8 islands. I think my major problem with the rivers is that you can't change the river mouths. It's a bummer to have to do a complete reset if you find you aren't happy with the river mouths. All the placements are good and fun to design around. I tend to like to have my design and placement of buildings be inspired by the natural map rather than doing a lot of terraforming and it's fun to try different maps and see how nice the different maps look when they are developed.
I'm not explaining it very well but I guess to be more brief, you don't always know the potential of the map until you have it pretty well developed. It can be an interesting revelation.