Personally, my favorite places to build are in plains biomes and Savannah.
Plains offers a ton of animal spawns, pls a ton of birch and oak, which are the main types of wood i use in my builds. Not to mention, most of the areas are flat and a bit hilly, so they are pretty decent spots for building bases, and towns.
Savannah biomes only offer acacia, which is fine, since i build with that a lot. I also like Savannah because it reminds me of the scenery of africa. Plus, They are usually flat in some areas, and in other areas, like mountains or extreme hill biomes, You can make cool sky bases that look pretty cool.