I prefer BoP because the biomes in general look better. There are some biomes I just hate, though. Cherry Orchards and Jade Cliffs annoy me the most, but there are several others I don't like.
As for those talkling about how ATG is "all the same biome", I'm not seeing it. I just started a new "Tech World 2" game & went into creative to explore and within 500 blocks of spawn I've come across the following biomes...
Grassland (spawn, with 9 IC2 rubber trees right there), Shrubland, Woodland, Spruce Woods, Frost Forest, Volcano (a MASSIVE Caldera), Alps Mountainside, Coniferous Forest, Wetland, Thinned Timber, Forest, Kelp Forest, Swampland, Lush Swamp, Hot Springs, Taiga, a TiCo slime island, and a weird little pach of jungle with only 3 big jungle trees. That's about half of what looks like a volcano island, like a cold Hawaii.