Large spanning sausage continents will always be there I think. Getting "clean" biome islands of mountain seem rather impossible with how the world is generated. Same for plains which always border other biomes.

On my map I have quite a few medium large pure black forest islands. Two medium large swamp islands not far from spawn. Easy to get on maps I believe.

From playing with the random button on map generator I realized there is no such thing as a perfect seed. Every seed have a little bit of everything.

I got some massive continents on mine, but also a lot of "damaged" biomes with thin swamp stretches and crap mountains. Tho the mountains that are worth my time are actually overwhelming. Plenty of very high mountains.

Also this map cries out for bridges and mined canals. Shallow water with rocks to run boat into is in annoying places. I consider map a work work challenge. There is also a continent looking almost like thors hammer :p

Take a look if you wish: mvD7LKLqE0
last letter is a zero.